Change or cancel from My account. Check the studio cancellation window.
Open My account → Appointments, find the booking and tap Reschedule or Cancel.
Most studios offer free cancellation up to a set window before your appointment - often 24 hours. The exact window is shown on each booking. Cancelling inside that window, or not turning up, may incur a fee if the studio has a cancellation policy. See No-show and late-cancellation fees.