hdd to small for update from win 7 to 10

Ok mate now can you go to Start > Computer (right click it) > Manage > Disk management and it will open into what I have made a pic of. Please send that back as a pic Screenshots and Files - Upload and Post in Seven Forums

Windows hdd data are
C type=basic file system=ntfs capacity=16.5gb free space=900mb overhead=0%
system reserved capacity=100mb free space=72mb
unallocated=20.6gb

Ok now from my angle so you are aware of my view of the problem what I don't understand is the reluctance to get a larger drive?? It would not matter if you had one just big enough or one that was more than enough and that for my part would rather get a drive that was at least twice the space that I need.
The thing is that from my own experience after losing a whole system by overfilling the drive it is just not worth the grief.
Now if for instance you only have a 60GB SSD drive even if you have an OS installed on it and plus the updates and probably all your programs you should have still enough space to download the 10 ISO and upgrade the 7 system. I do know what you are saying re minimum requirements - see this Clean Install Windows 7 .
However I would be very surprised if (unless you have an absolute ton of other data to put on) if you would use half the drive space. I just don't understand how you are managing to fill a 40GB drive with what you say your are. The other thing that crosses my mind is that a drive of 40GB is a most unusual size these days (just how old is this drive and/or do you have a problem with installing a SATA drive in) and one that used to be used many years ago until the data revolution started. I for example had an old Dell desktop with XP installed on a 60GB drive and a ton of pics and docs but came nowhere near filling the drive??
Having said that I would still like to see a pic of the Disk Management to work out what you said in the quote above because it really doesn't make it very clear - if we could see that it would make things so much easier.

Hmm well why not use Partition Wizard https://www.partitionwizard.com/free...n-manager.html and free up that unallocated partition?? That is going to give you 36GB to play with and I have to say that must be one quite old install media you have because SP1 has been included on the DVD's for a long time now.

There is a bootable PW too if you cannot install it on the machine

When you open the PW you just need to pick C: partition and DON'T do as in my pic it is only for example of what you will see and have to do to expand that C: partition.