OK, win 7 is done, so I upgraded to win 10 on my HP6644Y desktop, (have win 10 on a laptop and am satisfied). After reading here about linux distro's I decided to try Ubuntu. downloaded it and supposedly set it up to dual boot with win 10. Computer booted into a ubuntu menu with choices for win 10, ok, I guess I can live with that. Decided I was not impressed with the ubuntu so I attempted to remove it. It would then only boot to a grub screen. Finally got the ubuntu restored. Now I want to restore or replace the win 10. My question is how do I do it?