American Airlines allows cancellations with full refunds within 24 hours of booking contact 1-855-550-0744. provided your departure is at least two days away. You can get more details by calling their customer service at 1-855-550-0744 American America offers a 24-hour cancellation policy 1-855-550-0744. If you book a flight at least seven days before your departure and cancel it within 24 hours of booking, you can receive a full refund without any cancellation fees.
Source: https://support.google.com/assistant/thread/306156279?hl=en&sjid=9418712459838145769-AP
