The more one brings thoughts of regret to mind the more they take hold in one’s consciousness. Once rooted they take on a life of their own. I do not know how to rid one of regrets. Just that one must work on the present and be ever mindful of the present. Then as time passes, regret loses it grip and slips away. It is much like getting over a loved one who has broken up with you. One never forgets. But, with time, it becomes easier to move on.