Dual Boot - Two Vista Installations - delete one?


I am working on a computer that has two Vista Home Premium installations on the same drive. The original is on partition C: and the second is on partition D: . I am wanting to format the C: partition but cannot find a way to do this.

I installed EasyBCD and deleted the C:\Windows version from the entries list. This was successful in that it no longer comes up as an option when I reboot.

When I try to reformat the drive via the Computer Manager, or the Command Prompt it says either "you do not have permission" or "access denied."

I haven't messed with the Vista Bootloader in EasyBDC as of yet because I was afraid that it would end up messing up both installations of Vista.

What do I need to do to gain access so that I can nuke the C: installation? Can EasyBCD do this for me?

Thanks for your help!
You need to determine in Disk Management, which Vista is "system" (where the boot files are)
That's probably C: which is why you can't get rid of it.
If so, using EasyBCD 2.0 latest build / Diagnostics / Change boot drive, you can copy the boot files to D: and that will become system.
Boot D again so that the new BCD is used, then the C: partition should be clear for format.