Dual Boot - Delete a OS

How to Properly Delete a OS in a Dual Boot​

   Information

Deleting a double booted OS may seem simple - you just delete the partition with the OS you want to get rid of and you are done. Well, it is not that easy. With said approach you may get yourself into a lot of trouble. This tutorial describes a safe way how to properly delete a double booted OS.

Step 1 - Check where the bootmgr resides
Open Disk Management and find the partition that is marked "active". That is the partition that contains the bootmgr. If there are several active partitions, you have to look for the system flag - best seen in Computer.

The active partition is usually from the OS that was on the system first - e.g. if you installed Windows 7 on an XP system, the XP system would be the active partition. But there are also other cases.

If Windows 7 was the first OS on the system, then your bootmgr resides most likely in a separate system partition which is usually small.

If you installed Windows 7 as first OS to a disk that was not attached to the Sata port0, it can very well be that the bootmgr resides on an arbitrary partition on the disk that is attached to port0.

If you have e.g. a Dell system, your bootmgr may be on the recovery partition. Other OEMs may do the same, but I was not able to verify that.

This is the example of my current system. Note the two last partitions which are Windows 7 and Windows 8. The Windows 7 partition is marked as active. You also see that I have no small system partition because I have eliminated that partition after I moved the bootmgr from that small system partition to the Windows 7 partition.




If I would delete the Windows 7 partition, my Windows 8 would not boot any more because it would have lost it's bootmgr that is in cohabitation with the Windows7 bootmgr.

In order to avoid such an unfortunate situation, we launch the system that we want to retain and move the bootmgr to that system's OS partition. Here is how.
Step 2 - Delete the unwanted OS partition and reuse the space (Optional)
Stay in the OS that you want to keep and open Disk Management. Right click on the partition that contains the OS you want to delete and Delete Volume. Then right click on the deleted volume and Delete Partition. Now you should have "Freespace" where this partition originally was.

With Disk Management, you can define a new partition in that freespace or you can add it to the partition that shows to the left of that freespce. Just click on the partition which is to the left and Extend Volume.

If, however, you want to add that freespace to a partition that is to the right of the freespace, then you have to use an external tool. I suggest the bootable CD of Partition Wizard. Here is how.

A word of caution: before you manipulate partitions with Partition Wizard, make an image of all partitions on that disk. I once lost all my partitions on a disk because I made a small mistake manipulating one partition with Partition Wizard. For imaging I recommend Free Macrium. Here is how.
Step 3 - Cleanup the bootmgr
Now that we removed one OS, we have a surplus entry in the bootmgr. We will remove this entry with EasyBCD. As you can see in the picture, the operation takes only 4 clicks.

EasyBCD is a very handy tool for a variety of operations on the bootmgr. You should have that in your toolkit anyhow.






If you stop at this step, the MBR is still in a double boot configuration and when you boot, the BIOS will present you the black screen where you have to choose the operating sytem - although only one operating system is present. This is not a disaster, but it is an unnecessary step that requires your intervention.

The next two steps will reset the MBR to your current OS and then your system will automatically boot into that.

Important: You absolutely have to execute both Steps 4 and Step 5. If you only do Step 4, your system will not boot any more.

Step 4 - Clean the MBR




Step 5 - Reset MBR with the entry of the current OS

Related Tutorials

---

• How to Delete "Windows 8 Developer Preview" in your Dual Boot with Windows 7
• How to Setup a Dual Boot Installation with Windows 7 and Vista
• How to Do a Dual Boot Installation with Windows 7 and Windows 8
• How to Setup a Dual Boot Installation with Windows 7 and XP
• How to Setup a Dual Boot Installation with Windows Vista and XP
• How to Dual Boot Windows 7 and Ubuntu
• How to Delete an Operating System Listed in Windows Boot Manager
• How to Change the OS Name in Windows Boot Manager
• How to Recover a Partition Used by an Older OS in a Dual Boot

 

[Visaman321]

Hello, Charles here, I just created and format 2nd primary NTFS partition on same disk. I tried 2 rt click to delete but only options are extend or shrink. I can make( V active new partition i want to use. I have Windows-7 OS dvd disk to boot new drive. I will set BIOS to 1st boot cd rom my (d Just wandering if Windows CD will use. Or if there is another option.. My C: drive is corrupted. Tired of problems.. Thank for any input.

 

[mchldpy]

@ kimwu,

i followed your first link in post #37 to "resetting the BCD..." you stated "it was 'odd' they didn't tell you to rebuild the..."

i took this screenshot of the page you linked to. ('odd' you didn't see it)

michael clyde

 

[gregrocker]

I think you are OK in this regard. The bootmgr is on C (active partition). D is also an active partition, but the current bootmgr is most likely not there.

This is incorrect, as is the statement that it is the Active partition which signifies where the boot manager is located. It is the System flag which determines this. The active flag only points to the partition we want to hold the boot manager. It may not be moved there yet, or may be marked Active in error. In order to move it fully it requires running Startup Repair - Run 3 Separate Times or moving with EasyBCD per your tutorial Bootmgr - Move to C:\ with EasyBCD - Windows 7 Forums

 

[whs]

Thanks Greg for correcting that. I guess I was not looking into the details. I missed the second active partition.

 

[gregrocker]

No prob, Wolfgang. It also needs to be changed in the tutorial's first sentence:

Open Disk Management and find the partition that is marked "active". That is the partition that contains the bootmgr.

There may be several Active partitions on multi-disk systems. There are often errant partitions marked "Active." Yet the sole role of the System label is to show us the partition which is booting Win7.

 

[whs]

Right. I will change it. I forgot the case where several disks have active partitions.

 

[ThrashZone]

Is Easybdc available anymore ?
Can't seem to figure out where the download link is

 

[derekimo]

Is Easybdc available anymore ?
Can't seem to figure out where the download link is

If you scroll to the bottom and click on the register button on the left here,

https://neosmart.net/EasyBCD/

You can bypass the email entry and just click the download button to start the download.

 

[ThrashZone]

Thanks Derek I found it on TenForums too
But thanks for the instructions I was wondering about the registering bit too
Cheers.

 

[derekimo]

You're welcome, glad you got it.

 

[ThrashZone]

It worked
Can't believe I didn't screw that up :roflmao:
7 was already the default os switched that when the partition was 8.0
But once I upgraded 8.1 then win-10 over 8.1 win-10 was looking like it was taking over the boot default if I shut down instead of restarting,
On startup win-10 wanted to startup :/
luckily it flashed and went to 7 it was on 5 second startup
But that's when I said bye to win-10 for now until I get a dedicated external hdd to put it on ?
No biggie as far as I can see yet,
Cheers.

 

[gregrocker]

Mike can you post back a screenshot of http://www.sevenforums.com/tutorial...t-post-screen-capture-image.html#post2261610? Tell us what is on each partition as best you know.

 

[ThrashZone]

Okay,
A - was the original factory recover partition I formatted it for the hell of it,
C - is windows 7 with all programs and personal files/ Backup on an external as well and also a system image of just windows 7 not sure if personal files are on it :/
F - is where win-8-8.1 was originally and win-10 was installed on top of it/ empty now.
E or G - is the external powered off or I do have 2 flash drives so it could be them ?
View attachment 336674

 

[gregrocker]

Just a suggestion:

You could boot Partition Wizard CD, click on C to Resize, grab and slide C intact all the way to the left, Readjust the right border of C where you want it, click OK, Apply.

Then you should have enough space to install Technical Preview without it cramping anything for awhile.

I'm afraid you won't be happy with performance on an external which uses a slower USB controller.

Make a backup image first. Later run CCleaner then do a Puran Boot Time defrag with full Disk Check on both partitions.

 

[ThrashZone]

I thought of that (not that particular program) thanks for the recommend but I heard bad things can happen moving to the left so I left it for a future fresh install during the holidays,
I was supposed to do it last holiday season but chickened out

I did defragment everything before installing win-8 but I don't think I left enough room thinking of win-10 probably would of left 100 gig's in hindsight
Great idea though I might just do that sooner than later I'm getting a little more confidence as this year has gone by
Cheers.

 

[gregrocker]

I thought of that (not that particular program) thanks for the recommend but I heard bad things can happen moving to the left so I left it for a future fresh install during the holidays,
I was supposed to do it last holiday season but chickened out

I did defragment everything before installing win-8 but I don't think I left enough room thinking of win-10 probably would of left 100 gig's in hindsight
Great idea though I might just do that sooner than later I'm getting a little more confidence as this year has gone by
Cheers.

It is pretty risk-free with Partition Wizard. We've helped users do thousands of these same types of operations (even much hairier) without a single failure.

I just used it's Extend feature to equalize the free space between my 7, 10 and Storage partitions on a 240gb SSD. That is a very cool feature that lets you borrow space from any other partition or unallocated space no matter whether its adjacent or not.
How to extend partition easily with Partition Wizard - video help.

 

[ThrashZone]

When you put it like that I might do it tonight
I already have an system image and files backed up :/
Thanks bother
Cheers.

 

[ThrashZone]

Wow partition wizard is fast :shock:
Unfortunately Puran seems to come with Conduit attached or so says mbam ?

Looks different now only win-7/ programs/ personal files
I guess I should redo my system image now :/
View attachment 336683

 

[whs]

but I heard bad things can happen

That is a genuine risk. I once made a small mistake with Partition Wizard and it wiped all the partitions on my disk. Fortunately I had images of those partitions.

I since always recommend to make images of all partitions of a disk before partitions are being manipulated on it.

 

[gregrocker]

The screenshot looks good. If you are using Macrium or any flexible imaging app then you can adjust your current image to reimage to any size space. If you do a new one I would save the old one.

Puran is my favorite because of it's boot scan which gets at System files that would be running otherwise, it's Intelligent Optimizer (on Addt'l Operations tab) which moves Most-Used to the outer edge of disk, and the Disk Check to check the file system before defragging it.

I am sorry to see Vishal has added Conduit to Puran in order to pay for his efforts. Even though the box is greyed out you can choose to Decline this search spyware: