I've never tried to hypnotise myself to forget memories but have been able to change my feelings towards certain memories. I have memories that are over 20 years old, very minor things but quite often these memories popped up, causing me anguish and I felt it in the pit of my stomach. One day I decided to do something about them, and whenever one of those memories popped up, I told myself that it was a piece of rubbish, that I had to throw it away - I even physically used my hands to tear up the memory and throw it away. I still remember those things and do regret them but they no longer push me into the pit of despair.