Unexpected changes to travel arrangements are common. If you need to cancel your Allegiant Airlines flight for any reason, the Allegiant Airlines cancellation policy allows you to do so. If you cancel your ticket within 24 hours of booking, Allegiant Airlines will not refund you or charge you a cancellation fee.
https://flightcancellationpoli....cy.com/allegiant-air

Under American Airlines' name change policy, You can update your name on an AA ticket by phone. To begin, go to the AA official website and click the "need help" option, which will provide you with a customer care number. You will need to share your information, including your AA reservation number and personal information. After receiving your information, the agent will notify you about your ticket and whether you are eligible for a name change or not.
https://flightcancellationpoli....cy.com/american-airl