How are you supposed to forgive someone that did something wrong to you even though you know its in the past and forgotten?

Accept that the past is out of your control and it cannot be undone. Accept that people make mistakes and that they are flawed but you have to forgive them for their peace and your peace of mind and freedom.

It's clearly not forgotten, at least not by you. Chances are they have not forgotten it either. Start with forgiving the other person internally without confrontation. Once you have done that, if you feel the need to re-open the wound then definately give it a shot. If you've already forgiven them internally and they reject the face to face then you will still be at peace. Most likely you will find that they did not forget the incident and they accept your forgiveness.

Forgiveness doesn't always mean agreeing with, dismissing or accepting someone's actions. As an example, to some extent I accept that my abuser is a flawed individual and has major issues. He did many, many things that still hurt and haunt me, regardless of his intent or lack of such. I don't 'forgive' him exactly for hurting me or his refusal to get help for himself, but I accept that it happened. Unfortunately in my case, unless he changes for my own health I will eventually cut him off as much as possible. It all depends on if you want this person[s] in your life or not. So take into account the pros and cons of letting this person in your life, and if it hurts you more then it could help, don't feel bad if you have to cut the person out of your life. It's not selfish at all to put yourself first in that situation.

It's not always easy to forgive someone, instead sometimes it's just forgotten and pushed aside (so not really dealt with). Try to come to peace with what happened rather than with the person who wronged you.

If you hold onto something, then you are also holding yourself back. It goes back to "forgive and forget." You should forgive that person because being mad will do nothing positive. If the person did something wrong, don't forget about it and learn from it for the next time.

Understand they might have done it not purposely but if they had then maybe they are willinging to change who they are. You don't have to become best friends with them or anything but forgive them and move on.

This is not a one answer fits all. Its up to you to be the one to forgive and forget if you were placed in a difficult situation to where someone made you feel this way. You could try talking more with this person or seeking advice from a therapist or counselor if that person is worth it to you to do so.

You have to let go and realize that everybody is human and deserves a chance. If you want to remain the relationship that you have, you have to leave in the now.

You can forgive that person but never forget what they did, everybody is human and deserves a chance so I think you have to give them a chance to correct their mistake

It is difficult to forgive and forget such a person who did wrong to you. However, I would request you to forgive not because he deserves it, but because it will make you be at peace.