If your client needs to cancel a session you can follow these steps to do that.
Cancel a Multi Session
From the main menu click on Studio & Clients » Booking > Sessions.
Locate your session and click on it to see the details.
Click on the Booked session for this client.
Click on Cancel this Booking.
Choose Yes to confirm the cancellation.
Cancel a Single Session
From the main menu click on Studio & Clients » Booking > Sessions.
Locate your session and click on it to see the details.
Click on Cancel this Booking.
Choose Delete to confirm the cancellation.