Scenarios:
You want to modify a booking for an attendee in your activity
This document assumes the following:
Detailed Modify a Booking
Navigate to Activity tab select the activity, Click Bookings.
Select the Attendee(s).
Click the Action Cog, Select Edit Booking.

4. Toggle the date range and click update.
5. Now select or unselect the chosen dates in the Casual Booking calendar and Save Changes

Please note: If the customer has already been invoiced for the original booking, then Adjustment Items will be created.
Awesome! You now know how to modify a booking.