When an unpowered redstone switch is placed next an open door and then removed it will close it.

When a trapdoor, wooden door, or fence gate is open and any of the following are placed with the redstone output towards the door and left off then removed the doors will close:

lever, stone button, wooden button, stone pressure plate, wooden pressure plate, iron pressure plate, gold pressure plate, redstone repeater, comparator, tripwire hook

Redstone dust placed near an open door will also result in the same effect.