Letting go of someone doesn’t necessarily mean forgetting about them.
You can try to erase someone from your mind, and somehow those memories, the past still comes to haunt you. There will always be that canvas of a future you painted with that person stored somewhere deep in your thoughts. But remember that you do not have to hold on to that person if it makes you forget your own self worth. Don’t forget who you are just because someone else couldn’t see your value.