GIMP: can't delete gtkrc - please help

Hello,

I was trying to delete the entire portableGIMP directory from my USB drive and couldn't and was wondering if someone can advise on what I should do? I was able to delete all except 1 file called gtkrc and keeps telling me access denied. I was able to rename and copy the file, but unable to delete and change the attribute. Thanks for any assistance.

Thanks