"This also erases the history and very existence of the thing in question." oooooh
I'm going to have to say the Escapist background image. You know, the one you can't even see because there's a big light blue forum background in the way. Why? Well, see, I click on the very left of my screen, then hit home or pageup or pagedown etc etc to scroll. On the escapist however, it's a hyperlink. "Anthony Saves The World: Episode 10: Debbie Pt. 2" has just gotten 3 undeserved hits from me in my attempts to log in and read this thread, and I would like for them to understand that it did not, in fact, interest 3 people, so much as it was bad link placement forcing me to accidentally click it.
I'd love to have used this to better the world in a more significant way, but I dunno how removing a single thing could effect human nature. Churches maybe, simply for the sake of non-paradox it would mean people would have seen the idea of "a wizard did it" as unsatisfactory at the task of explaining things like, lightning, and clouds, and earthquakes. And thus, they would have no reason to congregate to worship the wizardly one who did it.