Temporarily boot from a Live USB/DVD and use its File Manager to delete the folder.
A Live CD/DVD or USB flash drive contains a complete bootable computer operating system (OS). When you boot a computer from it, the OS loads into, and then runs from memory instead of a hard drive. This allows you to run an OS without installing it or making any changes to a computer's current configuration.
To create one, download an ISO file containing the OS you want to use, (such as
Ubuntu,
Slax or
Zorin), then use something like
ISO Recorder to burn it to a CD/DVD or USB key.
Boot your computer from this disc/key and your computer will be running that OS instead of the one on its hard drive.
Now simply use its file manager to delete the folder, then reboot your PC from the hard drive as you normally would.