You can cancel your flight online at my excursions choice on the delta site or contact customer support at (802-278-0759). After the Cancellation of the flight, you will get a refund from delta according to the delta refund strategy. Refund of the ticket will depend on the type of ticket purchase, like refundable or non-refundable. You need to cancel the trip before 7 days of departure to get the maximum refund.