Forgive me but don't you need to cancel reservations within 24 hours otherwise you have to pay a fee?
Keeping the reservation but not USING the reservation just to get into the park early seems like an expensive way to get an hour (or so) of time in the park just to be at the front of a line for a ride.
I am also with
@JudyHopps about cancelling them as soon as possible. First to ensure I am not charged, but also so others could take advantage of the reservation as well. FWIW.