Southwest Airlines allows passengers to cancel their Wanna Get Away fares penalty-free within 24 hours of booking. Log in to your account on their official website, go to "My Trips," find your reservation, click on "Cancel," and confirm. For phone cancellations, call Southwest Reservations at +1-860-845-0471. Book directly with Southwest to ensure eligibility for their 24-hour cancellation policy as third-party vendors may have different policies.