This spell is meant for those who have a bad memory they wish to forget, and move on with their lives.
Turn off the lights. Light a black candle and place it so you can see both it and yourself reflected in a mirror. Visualize yourself putting a wall up between you and this bad memory. You are shunning it, pushing it out, willing it to leave.
Say these words or similar:
Remember the good
Banish the ill
Forgetting this memory
Is my will
Help me move on
Snuff out the candle and leave the room.
*Note: I'd like to say that some things in life are better not forgotten. Sometimes they plague our minds, but it's often better to remember and learn from it, than it is to simply forget and move on, having learned nothing. Use at your own discretion.