Is it okay to wish I could leave them all behind?
Why do you want to abandon them?
There is no future in relationships and the only constant in life is change.
It is not very nice to just simply abandon people in your past. Sometimes people naturally grow apart, but you do not need to intentionally ignore them. This seems a little forced.
If I don't remember the bad times, how else would I know what to avoid?
Remember your past and where you started, but don't dwell on it so much that it blinds you from moving forward. See tomorrow as a fresh start and if you need to leave your past behind, then do so momentarily.