You might be able to cancel your Allegiant flight without a penalty depending on when you booked([ +1(877) 559-0171] ) and the type of fare you purchased. Here's the breakdown:

Free cancellation within 24 hours [ +1(877) 559-0171] : Allegiant offers a grace period. If you cancel your flight within 24 hours of booking and your departure is at least a week away (7 days or more), you'll get a full refund with no fees, regardless of the fare type (refundable or non-refundable).

Non-refundable fares: If you cancel a non-refundable fare outside the 24-hour window, you won't get your money back. However, Allegiant will issue you a travel credit for the amount you paid, minus any carrier charges and booking fees. This credit can be used for future Allegiant flights.

Basic economy: Be aware that basic economy fares on Allegiant cannot be changed or cancelled after booking.

For the most accurate information on your specific cancellation options and fees, it's always best to check directly with Allegiant through their website or by calling customer service.