How to unregister Win7

#1
I bought win7 for my laptop because the previus Winvista that brought the laptop came damage. right now im about to sell my laptop because im looking foward to build my own pc for video hd editing. So i bought again a winvista to installed becuase i whant my win7 for my new pc. How do i unregister the win 7 in order to used in my neww machine.
 


This website is not affiliated, owned, or endorsed by Microsoft Corporation. It is a member of the Microsoft Partner Program.