Do you need to know what amount does it value to drop a United airlines flight? In case you have reserved a journey with United Airlines and do not desire to continue with it, you must be willing to know how to cancel your flight and apply for a refund. United Airlines Cancellation Policy is meant to assist with such issues. Under this policy If a traveller cancels their reservation within the time of 24 hours of purchase, then no cost is charged for cancellation.