How do you erase a person and every memory of them from your mind?

No, it's an impossibility. You will retain some good or bad memories of that person, but in time those memories will fade and not bother you as much as they once had. From every person we meet whether they are good or bad they leave an 'imprint' in your personality and you can learn from the bad traits of this person and know in your own heart that you don't want to be like that person or, you can learn some good qualities from good people.