There are no returns once booking and payment have been made. No right to refund or cancellation of a passenger's travel reservations exists.
Garuda Indonesia Cancellation Policy says Any trip cancellation must be notified in writing or by calling the Garuda Indonesia telephone number.
Only reservations made within 24 hours of booking can be canceled, provided the departure date is within 7 days at the time of cancellation in accordance with the airline's cancellation policy.

Here are some things to keep in mind about Indonesia's cancellation policy:

Check airline fees when booking your flight.
If you cancel your flight and are entitled to a refund, after cancellation fees have been applied.
If you need to change your flight, you can also pay. It is important to check the ticket for fees and restrictions before making any changes.
Under certain circumstances, such as medical assistance or military deployment, Garuda Indonesia may waive cancellation fees or offer alternative accommodation. It is best to contact the airline directly to discuss your options.