The criteria and conditions for cancelling a flight or changing an existing reservation are set forth in the Spirit cancellation policy. Customers may modify or cancel reservations as per policy up to 24 hours prior to the departure time. However, depending on the type of fare booked, any modifications made after this time will incur a cost. Additionally, cancellation requests must be sent directly through Spirit's website or customer service line, and refunds will be applied to the original source of payment within two weeks.
https://airlinespolicy.com/can....cellation-policy/spi