Yes you can cancel a flight on Southwest Airlines and get a full refund for the airline ticket as long as you cancel the flight within 24 hours before the flight is scheduled.
If you cancel the flight the same day of the flight then you'll have to pay a penalty but if you cancel 24 hours in advance then the full ticket price for the flight will be refunded to you.
The refund for the airline ticket will be refunded back to the original form of payment you paid for the airline ticket with.