If you only need to cancel one segment, first review your fare rules — changing or cancelling one leg can affect the whole itinerary. Log in to delta.com → My Trips, enter your confirmation, and view the itinerary. Select the specific flight leg and choose Change/Cancel — the system will show whether that leg can be removed and whether a fee or fare difference applies. If the site won’t let you cancel a single segment without voiding the rest, call Delta at 877-297-0699 and ask an agent to cancel only the requested leg. If you booked through an agent or third party, contact them first. After cancellation, confirm new e-tickets and any credits in writing.