Try taking ownership of the folder. Normally it takes a lot of steps, but I found a registry edit awhile back that adds the "Take Ownership" option to the shell (Right-Click Menu).
Download and unzip the package. You'll receive two files: An install file and a removal file - Run the install file. When prompted, accept the registry change. Then right click the folder you want to remove and click "Take Ownership." Click "Allow" (or nothing, if UAC is disabled), then try to delete the folder.