I have to sign off, so assuming you have Windows, here you go.
A) If you want to keep the installed programs, or you have Windows 7 or XP
1) Create a new user
2) Make it an admistrator
3) Sign off (or reboot), sign in as the new user
4) Delete the old user
B) If you have Windows 8 or 10 and DO NOT need the programs (this is an awesome feature)
1) In Windows 8, go to Settings
2) Choose ‘Update and Recovery’
3) Choose ‘Recovery’
4) Follow the instructions on the screen
1) In Windows 10, go to Settings
2) Choose ‘Update and Security’
3) Choose ‘Reset this PC’
4) Follow the instructions on the screen