How To Wipe An Already Transferred Mac

Let’s say you have transferred your old Mac to another person. Before doing the transfer you think you have erased all your old stuff. But, after the machine is transferred the other person discovers the Mac only works with your old Apple ID. Is there a way to fix this? It is a bit involved, but you can fix this problem. This article describes different ways to do it. If one of these procedures does not work, then try another one.