Activation is a protection mechanism implemented in Windows 10 and earlier versions against piracy. It first appeared in Windows XP and exists with different changes and improvements in Windows Vista, Windows 7, Windows 8 and Windows 10. When activation is successful, usually it indicates that your copy of Windows is genuine. There may be times when you need to deactivate your copy of Windows 10 in order to transfer your license to another PC. Here is how you can deactivate your copy of Windows 10.