Turkish Airlines imposes a flight cancellation fee if passengers cancel their flight after the 24-hour grace period. The flight cancellation fee is applicable to all passengers. If you cancel your flight after 24 hours of booking, you will have to pay cancellation charges, which depend on your route and fare type. The Turkish flight cancellation fee is between 150 and 300 TRY, depending on the fare type and destination. https://flightcancellationpolicy.com/turkish-airlines-cancellation-policy