Unless the terms of the instrument creating the power of appointment or the instrument exercising the power of appointment provide that the exercise is irrevocable or unamendable, a powerholder may revoke or amend an exercise of a power of appointment made by an instrument effective during the life of the powerholder where the exercise is to become effective at some future time or contingency and where that future time and contingency has not yet occurred, as long as the revocation or amendment is done with the same formality as the original exercise of the power of appointment.
Utah Code § 75A-4-314