Can hypnosis be used to help people erase their memories?

I read somewhere that this is possible. Is it true?

If so, how much can be erased? Could they erase a year or more? If someone wanted to, could they get a trained hypnotist to erase all their memories so that they're essentially a blank slate? I assume the latter is impossible, but I figured i'd ask just in case. It'd be great if that could be done.