If you wish to erase everything from the hard drive, then here are some options that you have:
a) Check if you have a recovery partition on your hard drive. If you have one, run a full system re-image which will take the computer back to the factory defaults after erasing everything off it.
b) If you do not have the recovery partition, use the Operating System Disk to format and reinstall Windows on the hard drive
But before you try any of these two options, please make sure that you have backed up all the necessary information that you do not wish to lose
Here’s to Good Karma