It's not a task one can do logically, let alone in fact. One cannot disprove everything imaginable, and that would be my point as an atheist.
You are setting up an impossible situation. Then you act as if impossibility discredits the very skepticism you are giving creedence to. This is exactly why, quite often, atheists say there is no "belief that God doesn't exist." There is simply a lack of belief in God, which is exactly what makes it a valid view. Any other view leaves one chasing his or her tail in erratic mind games.
Unfortunately for theists, one needn't even assume a God exists, let alone attempt to prove it through science.