Within 24 hours Yes, Singapore offers a 24-hour risk-free cancellation policy. You can cancel any flight within 24 hours of booking for a full refund, as long as the flight was booked at least 7 days before departure at +1-833-444-7613(US) OR [UK] +1-833-444-7613 Does Singapore Airlines have free cancellation?
https://www.devex.com/people/how-late-can-i-cancel-my-singapore-airlines-flight-singapore-2195521
