It is either a good memory or a bad memory, positive or negative, joyous or depressing, angry or compassionate. Rarely are you able to just let a memory be. Releasing judgement of the memory you wish you could forget is an exceptional way to let go of the negative space it holds.
What you focus on grows, so it is important to acknowledge that when you give your attention to an undesirable memory (or song, or face, or…) that memory becomes larger and larger in your mind.
By redirecting your thinking to another song, memory, experience – ideally one with positive connotations – you can train yourself to spend less time with your magnifying attention on something you wish you could forget.
As soon as you catch yourself recalling an unwanted experience, redirect your thoughts to an upbeat one. Over time, your brain will create new neural connections uniting these events and will naturally begin to connect the negative memory with the more positive one.
Meditate on positive circumstances and make a note of the emotions you feel. Keep this list handy, and mentally redirect your thinking the next time a negative memory is brought to your attention. It may take practice, but a new perspective on an old memory is very well worth the effort.