Although customers have the potential to cancel the flights anytime before departure. But they must know the Delta Cancellation Policy mentioned below when it's about healthy cancellation.

• First and foremost, 24 hours of booking is the risk-free or restricted duration to cancel the flights.
• Secondly, one must cancel the flights within the restricted hours and avoid cancellation fees.
• The cancellation is deducted from the refundable ticket.
• Non-refundable ticket holders must pay the extra on cancelling the flight after the limited hours.
• The Cancellation fees rise as per the passing hours of booking.

To know more about it read the full Blog. 

Source :- https://www.zupyak.com/p/3287423/t/know-about-the-delta-cancellation-policy