Online Cancellation of a Southwest Flight:

Access your Southwest Airlines account by logging in or type Flight cancellation(https://cutt.ly/cKZ4xvf) into the search bar.
Choose "Flight" from the drop-down menu, and then click "Manage Reservations."
Include the first and last names of each passenger, along with the confirmation number you received after finishing your reservation.
Choose "Cancel Flight" and then click "Continue."
If your flight qualifies for a refund, it will be made clear in a pop-up box on the following page. Your flight will also be cancelled.

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