I have to say that I believe the Seth version about probable selves with regard to altering the past.
The best analogy I could use to describe this would be the movie "Back to the Future". After going into the past and encouraging his father to take action against the school bully, Marty's (Michael J. Fox) life is completely altered upon returning to the present. You all know this movie.
By activating a probable past event (exercising assertiveness versus passivity in a crisis moment), a different path was charted for the father. This had profound effects on the entire family's future.
In the same vein, "The Family Man" with Nicolas Cage (a great holiday-time movie if you haven't seen it) profiles a rich but single New York investment broker (Cage), who falls into a probable past and experiences what his life would have been like had he married and had a family at an earlier point in his life.
In either example, the you in the present now has changed the past and are experiencing one of the probable courses that change may have engendered in the present moment. There is no past event to erase, as you have not experienced it or have literally altered it and removed the undesirable elements/choices. The only difference here is that in the movies mentioned, the present moment personality remains aware of the changes made to the past, and can then appreciate the effects in the present moment. In reality, changing the past happens ALL THE TIME, and you can allow yourself to become more aware of it by focusing on some of the differences in remembered events between yourself and others.
This can become very apparent in meetings with people you have not seen in a long time, when you discuss the past, and find that their memory of past events is quite different from yours. The past HAS LITERALLY CHANGED for both of you.
I believe that much of what is being discussed here is more or less releasing the energy or letting go of the lingering negative impact of a past event, as opposed to actually altering the past.