A Purpose is a fixed automatic action (in response to certain circumstances).
Since they are fixed, they are not a good match for reality (which changes continually).
Purposes get stuck on parts of oneself due to shocks. So erasing them can be done by erasing the shock, the original action of the cause of having the Purpose, the fall down the scale-of-created-things, all uses of the Purpose, and its structure (existence), which is a set of linked points.
Purposes can result in other types of non-ideals.