American Airlines Change Flight or American Airlines Cancellation Policy: American Airlines has eliminated virtually all fees when you cancel a flight or change a flight.
Air Canada Cancellation Policy : Air Canada does not allow flight changes for those with basic economy tickets after the initial 24-hour window. .
Delta Cancellation Policy- Delta Cancellations policy for non-refundable tickets allows passengers to cancel their tickets within a day of flight booking without paying any fee.
https://aviationrepublic.com/blog/american-airlines-change-flight-date-policy-fee-reschedule-booking/
https://aviationrepublic.com/american-airlines-cancellation-policy-how-to-cancel-flight-booking-with-aa/
https://aviationrepublic.com/blog/air-canada-cancellation-policy-how-to-cancel-an-air-canada-flight-booking/
https://aviationrepublic.com/blog/delta-airlines-cancellation-policy/