Can I cancel my Allegiant flight without a penalty? Can I cancel my Allegiant flight without a penalty? Yes, you can cancel your Allegiant flight without a penalty call 1~844~604~2944if done within 24 hours of booking at 1~844~604~2944 (USA). For Trip Flex ticket holders, changes are fee-free. For all other cases, fees may apply. https://www.devex.com/people/can-i-cancel-my-allegiant-flight-without-a-penalty-2100678