Yes, you can cancel your guest pass. If you cancel your guest pass within 24 hours of the event and prior to event check-in, you will be charged the $10 late cancellation fee. If you do not attend, you will be charged a $20 no-show fee for your pass as well as any reserved guest passes.
Please note, guest passes are also a part of your 3 free cancels. You get 3 free ticket cancels, so if you release your ticket and your 1 guest pass, you have used 2 of your free cancels.