So today is the day ... I looked around and cannot find any related feature on their WEB pages.
Am I missing it, does anyone know how to do it?
It's working for me. Log into your EpicPass Account on the web. Open the Season Passes tab. Select the submenu Reservations and you will see a list of all of your current EpicPass reservation days. Next to each reservation day in this list is an option to cancel the reservation.
No need to drop into the interminable EpicPass phone lines or chat queues!