How to ensure none of my old posts pop back up on Facebook?

So awhile back I reactivated my Facebook so I could message some old friends. I hadn't been on in awhile, and I guess there's this new feature called Memories or something? It went back and started bringing up these really old posts and putting them on my Timeline for everyone to see.

The issue with that is is that it brought up some stuff from when I was talking to this one girl in high school (happened over 4 years ago). My gf saw the stuff and got kinda upset, so I want had to deactivate my Facebook to avoid a fight.

My question is how do I turn this feature off? I looked and looked and couldn't find where I could turn it off. I removed the old posts manually off my timeline, but my friends said they could still see the Memories posts and the stuff I'm tagged in. I really just want to clean all this up and not have to start a new profile.