Delta is famous for its risk-free cancellation policy according to which a customer will be given his refund in the original form of payment if a cancellation is made within 24 hours of booking and the reservation is made more than seven days in advance of departure. So if you have booked your ticket with Delta and want to cancel it, make sure that your cancellation request is made by midnight of the day after the ticket is purchased or midnight of the departure date of the first flight. Also keep in mind that their risk free cancellation does not apply to travel agency bookings, paper tickets and reissued tickets.