Uninstalling Thunderbird EULA after installation in wrong location

Okay, I did something stupid. I thought I'd give portableapps.com Suite a try as a new user on a new flash drive.

1) I downed the suite, all 100+ MB
2) Plugged in the new Flash (yes, I erased all files on it first)
3) Invoked the Suite installer and of course it asked where did I want to install.
4) Found Drive D of the 1GB size (I thought, great) and installed
5) Only after I pulled the flash out did I find that the plug contacts were broken off inside the flash housing (I wondered why its light didn't blink during install)
6) Still, there was Drive D with the completed installation. ONLY THEN, did I realized, that the installer created a partition on my hard drive because of course it didn't see the broken flash drive at all, and the installer labelled a new partition on my "C" Drive, called it "D" and installed there.
7) I threw the broken Flash in the trash
8) Read John Haller's comments on un-installing: just delete the two folders and other installed exe's and you're done --or-- format the drive. Sounded easy.

NOW HERE IS THE ISSUE:

9) I feared that Formatting the 'D' Drive would delete the entire physical Drive which is my main C Drive. So, I opted for John's suggestion to just delete the files. All went fine until one file, the EULA.TXT for Thunderbird. The file won't let me change it's name or delete it.

10) How (okay dumb question) can I delete that danged EULA.TXT file? Or if I cannot do that can I format the 'D' drive which is really a partition without deleting my entire C drive???

Yes, I bought I new Flash drive now, so am ready to try the PortableApps.com Suite again.