You can cancel online.
All of the points will be returned to the UY in which the reservation was to take place. As long as you cancel 31 days or more before check-in, the 2017 UY points will be bankable if within banking window. If 30 days or less, all points go into holding. The points banked into your 2017 UY will need to be used before the end of the 2017 UY or they will be lost.