To take a thing out of what was chosen. Deselection restores an option that had been closed.
Latin de- (reversal) + seligere (to choose apart, select), from se- (apart) + legere (to choose, gather); to take a thing back out of what was chosen, restoring an option that had been closed off.
Latin legere is to gather, and deselecting ungathers one thing from a set without touching anything else still held. It restores exactly one closed door, and no others.