I see no reason to try and actively remove thoughts and memories. I personally believe we can work so hard at trying to live in the moment that we forget it was all those past memories that helped us get to this point. Why shove them away? Maybe your subconscious is telling you that you need to forgive those old friends or make amends to go further. Maybe they’re there to remind you what happened when you wound up in an unhealthy relationship and it’s telling you to be careful. Maybe they’re just popping in your head to remind you that you used to love baseball and should catch a game. Listen to your thoughts- there are lessons to be learned at every level if we’re willing to listen.