According to United 24 hour Cancellation Policy, non-refundable tickets cannot be returned unless and until they are cancelled within 24 hours of purchase, as long as the flight's departure time is not more than two days after the cancellation. Additionally, basic economy tickets for both domestic and international flights are not subject to cancellation or modification fees. Any cancellation made within 24 hours after the purchase will be a full refund, no deductions. Using United 24 Hour Cancellation policy, individuals are allowed to receive a refund with no penalty for cancelling; this is only valid if the cancellation is made within 24 hours from the time the tickets were booked. 

Customers who cancel their tickets within 24 hours of the purchase date are entitled to a full fare refund under United 24 hour cancellation policy. With United Airlines' 24-hour flexible booking window, you can alter or cancel your travel plans up to 24 hours before the scheduled departure time and receive a full refund on the original method of payment without incurring any cancellation fees. If you cancel within 24 hours of making your reservation, you will receive a full refund without any costs. This is only the United 24-hour cancellation policy.