I don't know that this is physically possible although a fascinating idea (it was the premise of a movie - Eternal Sunshine of the Spotless Mind). In reality though repressed memories eventually come back and can be re traumatizing when they do. People who have legitimately lost their memories of traumatic events usually have because of a brain injury, which involves more than just memory loss and is not a good thing.

I don't see why your T can't help you come up with ways to reframe memories though. Like other posters said, EMDR is supposed to be very helpful and some CBT therapies can be too.