(16M) I want to reconnect with an old friend, but I'm not sure how, any advice?

I had these two friends growing up until I was around 14 when they started being really horrible about me having other friends so they got very mean so I decided to cut them off. I was speaking to one of them a few days ago on a school trip as we have friends in common and we were speaking fairly normally. I have the other friends number still and I always got on with him more than the other guy, I want to let him know there's no hard feelings anymore and how I ended things wasn't right (I was angry and irrational) but I'm not sure how to initiate it. Can anyone help?