I need to factory restore a Dell desktop. Originally it was running win 7 or windows 8. The ckient upgraded to win 10 and it is running so so slow. So I decided to factory restore the desktop. What are the key stroke I need to use to boot up in recovery mode and format this PC ? Ate the key I used for win 7 or for Windows 10? They did the upgrade more than 30 day ago so I don't see the option to undo anymore .
Just in case where should it. E the option to undo the upgrade to win 10 please