Thank you for your question!
This is not like “taking a pill” and get better all of the sudden. First the disease of waste thoughts have to be realized and perhaps when it comes in its most advanced stages, we can “get rid of it” by no resisting them or fighting them that is, through being awake, aware, conscious when they arise.
Experiment. Walk around and then your friend says hello to you. You can say hello back, but watch the whole scene including your role with the consciousness that it is a “role.” if there are waste thoughts after that, those are not your thoughts but part of the role.
If you do not identify with those thoughts, then you are “getting there.” As you add further consciousness, as you are awake at every moment, then that waste will not be there unless you are “sleeping.”
It is true that a “sanskara” is the cause of those waste thoughts, but knowing that it is a “sanskara” doesn’t do anything to understand why those waste thoughts emerge. Moreover, there is no need to understand why they emerge, but only that they are “there” but that those thoughts are not related with you, that is your identification with them has been “cut off.”
That is all. Let the thoughts appear, be conscious, be awake in witnessing them as if you were watching TV; the stuff is going on in the TV, but that only affects you unless you identify with the TV program. The same is with life… you can create all sorts of waste thoughts about why the actor didn’t act in another way or fantasize with the stars of the program…the TV program has already been made the way it was broadcasted… The movie of life is in essence another TV program but commercial free! 🙂