Southwest Airlines allows you to cancel flights up to 10 minutes before the scheduled departure time. If you cancel before this deadline, you may receive a refund or travel credit depending on your fare type and whether the cancellation is voluntary or due to a significant delay or cancellation by Southwest. If you don't cancel before the deadline and don't show up for the flight, your reservation will be subject to the no-show policy. 

Key Points:

• Cancellation Deadline:
  You must cancel your flight at least 10 minutes before the scheduled departure time. 

• No-Show Policy:
  If you don't cancel and don't fly, your reservation will be subject to the no-show policy. 

• Refunds and Travel Credits:
  Depending on your fare type (Wanna Get Away, Wanna Get Away Plus, Anytime, Business Select) and whether the cancellation is voluntary or due to Southwest-initiated changes, you may receive a refund or a travel credit. 

• Significant Delays/Cancellations:
  If Southwest significantly delays or cancels your flight, you may be eligible for a refund, even for non-refundable tickets, and for reimbursement of certain optional travel charges. 

• Rescheduling:
  If you need to reschedule your flight, you can do so online or through the mobile app for bookings made through Southwest's website or app. 

Partner Bookings:
If you booked through a partner airline, you'll need to contact the partner airline to make changes or cancellations.