How do you delete folders and files from the "Program Files" folder in Win 7?

I am trying to do this on someone else's computer and I don't know what rights their user account is.

It says that I don't have permission to delete the folder. I thought it was an administrator account because when I do "Run as Administrator" for other things it doesn't ask for a password, so it must be an administrator account.

Should I be able to delete a folder out of "Program Files" if the account has administrator rights? Or do I need to do something else, such as "Take Ownership" of the folder.