People are taught to us association as a mnemonic device to help them remember things.  Well it appears you can do something similar to help you forget:

The experiments started with MacLeod and Noreen showing their subjects a series of different words — “barbecue,” “theater,” “occasion,” “rapid,” for example — and then telling them to generate one specific personal memory in response to each word.

There were 24 words in all, and after the subjects had described their memories, they were all sent home and told to come back a week later.

The following week, when they returned, they were given a transcript of each of the memories they’d shared, along with the specific word that had generated it. They reviewed the words and memories until they knew exactly which word went with which memory, and then were put in front of a computer and told that they would see each of those words flash on the computer screen in front of them.

If the word appeared in green, they were to repeat the memory associated with that word out loud, but if the word appeared in red, it was very important for them not to think about the memory associated with that word.

MacLeod and Noreen showed the subjects 16 of the 24 words over and over and over. Each time a subject either repeated the memory or blocked it. Some people apparently pictured a blank; others distracted themselves with other thoughts.

‘A Significant Forgetting Effect’

At the end of this process, the subjects were tested to see if there was a change in what they recalled. And there was — in the memories that had been repeatedly blocked.

“There was a significant forgetting effect, about a 12 percent drop in the level of details recalled,” MacLeod says. “That’s a large effect.”