Plot hole? (***Spoiler Alert***!!!)
Perhaps someone can clear this up for me, or confirm that this seems like a (large) plot hole:
How does "forgetting" the sphere and their experience remove their powers? It took them awhile to figure out they were causing all the horrible events and link that to the sphere. By forgetting the sphere, all they would do is erase their ability to actually understand / control their powers!
They will still have fears, desires, etc, and will cause a lot of freakish things around them, and probably kill themselves in some creative way.
The only explanation I can think of is that by the sphere leaving, their powers would leave, too. But they wouldn't have known that (necessarily) before deciding to forget.