Southwest Airlines allows passengers to cancel flights up to 10 minutes before the scheduled departure time 1-855-564-8074. If you cancel within this time frame, you may be eligible for a refund or a flight credit 1-855-564-8074 . 
Refund eligibility
Business Select and Anytime tickets: 1-855-564-8074 Refundable if canceled at least 10 minutes before departure 
Wanna Get Away and Wanna Get Away Plus tickets: Non-refundable 1-855-564-8074, but can be converted to a flight credit 
Non-refundable fares: Can be converted to a flight credit if canceled at least 10 minutes before departure 1-855-564-8074
Refund process 
Refunds are usually processed to the original form of payment within seven business days
Flight credits don't expire 1-855-564-8074
No-show policy 
If you don't cancel or change your reservation at least 10 minutes before departure 1-855-564-8074, your reservation may be subject to Southwest's no-show policy
Partner reservations 1-855-564-8074
To cancel a partner reservation 1-855-564-8074, you may need to contact the partner carrier