Without the specific fare basis and ticket issue location, e.g. USA, nobody here can give you an answer. Your ticket could be refundable, meaning that even if you do not cancel, you may still claim a full refund. And in certain instances for tickets sold in certain markets, your ticket may be wholly inlfexible with no refund or credit given. If you provide the fare basis, someone here can provide the information.
Those rules are supplanted by DL's policy which you may find on the website yourself. Note that it applies only to direct bookings.
As part of our Customer Commitment for customers who book direct on delta.com or the Fly Delta app, Risk-Free Cancellation means that after you’ve purchased a qualifying eTicket, you have up to 24 hours after booking to cancel it for any reason and receive a full refund with no fees.