If you want to cancel a flight with United Airlines, you must consider United Airlines 24 Hour Cancellation rule.United Airlines will finish up the discount on your ticket when dropped in somewhere around 24 hours of procurement. In any case, a few banks or Mastercard backers might start a transitory hold of your assets on your charge or Visa. We urge you to contact your card backer for their particular arrangements. Please go through the terms and conditions for more details.