It is possible to cancel Allegiant Airlines both online and offline. It's difficult to cancel a vacation plan and withdraw a pre-purchased flight ticket. We don't want you to have to deal with it. This is why our customer service representatives are here to assist you with your Allegiant Airlines flight cancellation. We will make every effort to guarantee that you get your flight cost and that you do not incur any further cancellation fees. You may also call Allegiant Airlines' customer service department, and their knowledge will guide you through the entire procedure. The theme is available 24 hours a day, 7 days a week, so you may contact them whenever you want. See at: Allegiant Airlines Cancellation Policy See also: Southwest Airlines Cancellation Policy || Hawaiian Airlines Cancellation Policy