If you have Turkish Airlines tickets that you need to cancel for personal or urgent reasons, you can do so by taking advantage of the airline's accommodating cancellation policy. Making the most of Turkish Airlines Change Flight which permits bookings to be cancelled within 24 hours of the original purchase on the same day without incurring any cancellation fees, will benefit customers greatly. Customers who do so will be eligible for a full refund, with the stipulation that the booked ticket must be made at least seven days prior to the flight's scheduled departure. When cancelled within 24 hours of departure, all refundable and non-refundable tickets are eligible for a full refund.
https://www.travomojo.com/flight-change-policy/turkish-airlines-change-flight-policy/