win 7 x2 on one hdd, can't remove one.

problem:
I have two partitions on one hard disk, both have windows 7 on them. I want to delete one partition (and the OS) so that it can be merged with the other. I cannot delete the partition i want because it's "(System, Primary Partition)". The other partition doesn't seem to have the System label and I'm wondering how to remove or move the system label so that the partition can be deleted.

solutions tried:
Looked through options in the computer management GUI.

other info:
I currently have one account (the administrator account) however i find i cant delete any files on the partition that the other OS is on. I also cant delete any files that OS put on my external drive. I messed around with the privileges but no joy.

update:
After an hour of messing around i managed to format the partition i wanted and remove the volume. However with almost 300gb of unallocated space for some reason the partition right next to it can expand into it? However i can create a new volume and format that.

current:
Made a new volume and formatting (non quick format to remove all data).

No joy with the full format, seems to have done a nice job of removing all the data, but cant expand my windows 7 partition. Going to sort out all my files (lucky i have 2x 1tb external drives) and do a clean install on my other hard disk.

What a shame, seems that Microsoft didn't do such a good job with this part of windows.