The following guide will step you through what Microsoft calls recycling of your PC. Essentially these steps will get your PC ready for resale or giving to someone else.
[_] Windows 8 system
[_] Administrative account
You can also check this video walkthrough for resetting Windows 8 to factory settings:
1. Bring up the right side context menu and select 'Settings'
2. In the 'Settings' menu select "Change PC settings"
3. In the 'PC settings' popup select 'General'
4. In the 'General' section scroll down to 'Remove everything and reinstall Windows...' and click [Get started]
5. On the 'Reset your PC' screen click [Next]
6. If you get the 'Your PC has more than one drive screen' select the appropriate option. If you wish to destroy all data click [All drives] if you wish to only restore windows, and wipe all data on that drive, click [Only the drive where Windows is installed]
7. You'll now be asked to either [Just remove my files] which will only destroy your data, or [Fully clean the drive] which does to full system wipe. (For this tutorial we'll be choosing 'Fully')
8. Windows is now ready to 'Reset' your PC. Read the warning, and to continue click [Reset] to stop this process click [Cancel](there is no going back once you start the 'Reset' process.)
9. Windows will now start the long process of resetting your entire PC, all files, software, users, and apps you have installed will be gone, and the PC will be like the first day it was purchased.
10. If you are going to sell, or donate your computer power it down at this point and it'll be ready for the new user. If you were just resetting it complete the steps requested to get re-setup.
'Resetting' your PC is a great method for getting your PC ready for sale or donation, it removes your data and resets Windows to its factory defaults. Please be warned though, it may be possible for data recovery in some instances, if you have any highly confidential files, make sure they are wiped using a file shredder prior to executing this guides steps.