I think first you must start with Seth’s fundamental definition of experience: the simultaneous NOW moment. We experience time and space while in framework 1/ physical reality, but in framework 2 we experience the simultaneous now. This is the fundamental reality.
In this sense, time, past and present, are “constructs” of physical reality. They are offshoots of our particular neurological makeup. We experience time because we are designed to exist within such a framework, not because time is objectively “real”.
So I believe that Seth is simply saying that, from the position of the here and now, which is your point of power, past events only have the reality that you give them through your beliefs about them.
As regards another person’s reality, you can only “control” how you intersect. You cannot control another person’s experience, beliefs or intent. We are each distinct in our own self awareness, our sense of “I am-ness”.
What you are describing is, in effect, a kind of psychic murder. You want to eliminate a person as if they never existed. You cannot do this and you should deeply examine any such resistance you feel toward another.
However, you can change your experience of the person in the now and thereby change your “memory” of the person as it extends outward from the now. And you may go forward as if the person never existed, but you cannot erase another person. This would be solipsism which is definitely not what Seth is implying at all.
All things retain their own life and existence once they are realized. Your past will not cease to exist, but that does not mean it must remain a part of your own experience in the now if you deem it should not.
This is particularly important in cases of past trauma. It sometimes seems as if a traumatic even continues to have tremendous power in the now. But it need not. The effect of past trauma can be minimized to the degree that the effect is within the psyche only. Physical effects may sometimes remain, such as in war, but even these can be seen with different eyes, if one so believes.
No one is a prisoner, not to an idea, a memory, or another person. Even if current “evidence” might suggest otherwise. Once someone is ready to let go, as in an abusive relationship, and change the beliefs that have led to current conditions, one may let go. To paraphrase Eckhart Tolle (who was probably paraphrasing someone else) “how do you let go of a hot ember you are holding in your hand?” The answer is obvious.
I find the answer given by inavalan of interest because Seth continually reminds us to trust “our own impulses” because such impulses come from the “entity” which can be viewed as the “inner guide”, sometimes referred to in religious terms as the guardian angel.
Certainly there are caveats here, such as with persons who have deeply troubling and limiting beliefs about the self, good or evil, religion and demons, etc. One must first cast off such limiting core beliefs, such as the notion that man is basically evil and in need of salvation, etc. and reclaim the personal power that comes from realizing the multiverse is fundamentally good and that all things can be changed in the now moment.