United Airlines allows cancellations with full refunds within 24 hours of booking, provided your departure is at least two days away at 1-844 UA (604-2944) For non-refundable tickets, you can make changes or cancel without a fee, but you will receive a travel credit instead of a refund. https://lacdmhowr.powerappsportals.us/forums/general-discussion/12382301-44a7-ef11-b542-001dd8097a1a