If the ticket is issued on BSP (Billing and Settlement Plan), in that case ticket can be cancelled on the same day. Cancellation of the ticket can be done before 11:49 PM, and a small cancellation fee has to be paid by the passenger. One has to pay $30/passenger for cancellation of the ticket. If you want to cancel the ticket after the said time, then it is will become a non-refundable ticket.
If the ticket is issued on ARC terms then tickets can be cancelled within 12 hours. Passenger has to pay small cancellation fee. $30/person has to be paid while cancelling the ticket. If you fail to cancel the ticket within the mentioned time then the tickets are considered as on-refundable tickets.