On the Calendar, hover over the appointment, an information box opens up, there you click on Cancel
You will reach the appointment editing page where you can specify why you are cancelling the appointment. You can also delete the appointment by clicking on Delete Permanently. (We recommend cancelling appointments instead of deleting because then you will always have a record of the reason why the appointment was cancelled.)
Once you are done, click on save. You’ll reach the calendar again. And the cancelled appointment will be greyed out
Hide Cancelled Appointment
If you don’t want to see cancelled appointments on your calendar, on the bottom left, uncheck “Show Cancelled Appointment“
And the Cancelled Appointments will disappear.
They are still recorded but don’t clutter your calendar.