Unfortunately, no one can travel back in time to change what they did in the past. Linear time, though often thought of as a construct of the human mind, has an effect on our spiritual lives because we are manifest, or embodied.
Our physical being responds to linear time, as does our soul while incarnated. Therefore, sequence, which occurs on the linear time line, is essential and real in our spiritual lives.
Of course you can regress back to any time in your present life, and it's very helpful. Most psychotherapists are trained to guide you. While you can't change anything back then, you can change your present response to what you did. You can change how you carry the weight of your actions.
Change occurs in the present moment. When you see your past, you can gain wisdom and learn from it. You have a new perspective now. You have distance from the triggers that led to your actions.
You gain empowerment from your new understanding. You can make amends, and move forward with strong, clear intention into the actions you now choose to take.
Don't get stuck in the past: use it to learn from, use it to fuel your growth in the present.