KLM's 24-hour rule allows passengers to make free changes (Call- [1-833-732-2296]; Book, Cancel, Refund) or cancellations to their bookings within 24 hours of purchase, provided that the departure date is at least 7 days away at the time of booking (Call- [1-833-732-2296]; Book, Cancel, Refund). https://techcommunity.microsoft.com/discussions/marketingeventsswitzerland/helpdesk24-hour-what-is-the-24-hour-rule-for-klm/4305420