HP Beats Special Edition 15"

Hello,
When I was factory resetting my laptop halfway through it blue screened said it needed password 4 email account I don't know what it would be as it's been very long time that I set this up. A friend wanting to buy it I need to finish factory reset in it I need to know how to get past the blue screen to finish factory resetting I have got to the point where I could and it quits at about 47% and ask for password to my Gmail account which I have no idea what it could be I've tried everything anybody out there please help me