Tickets can be cancelled up until 24 hours after the event has ended.
If the ticket cancellation button is not displaying on Sales List, it is possible that the attendee has already checked-in. If you wish to cancel a ticket that has already been checked in, please first go to Attendees tab and click the "Undo Check in" button. After that, the cancellation button will re-appear on Sales List. For more information on undoing a check in, please see Name Search Check-in.