Need help Loging into a PC with my account.

[RebeLing]

My friend gave me FAF on Steam and a PC to play the game on. I have been trying to link my account to steam and log in following the directions in the link. I can't link my account to FAF because the PC I'm on is already linked to his account. When I link with steam it gives me a message saying my account is linked but when I log into the FAF client it tells me the PC is already linked to a different account and that I need to link it to steam. please help?