Acceptance deadline and the waitlist

<p>I was just waitlisted at my first choice school. I was accepted at another school a while ago, and have until May 1st to respond, by which time I must submit the deposit (which the school considers a "commitment to matriculate"). As unlikely as it is, if I were to be accepted off the waitlist at my first choice, how would I turn down the school that had accepted me earlier? Would this be possible?</p>