Cancelling a Ticket Reservation or Purchase within 24 hours of Booking. For airline tickets that are purchased at least seven days before a flight's scheduled departure date and time, airlines are required to either: allow consumers to cancel their reservation and receive a full refund without a penalty for 24 hours,
https://portal.u-blox.com/s/question/0D5Oj00000TBkzoKAD/united8888291467-what-is-the-cancelation-policy-for-united-airlines