To arrive an Individual Booking, from the Retail Point of Sale Screen:

Select Bookings.

Locate the booking you wish to arrive and open the booking.

In the Ar column to the right of the name, double-click to view the drop-down box.  In this box select the option 'R'.

Select F9 Arrive.

When you select this option the charge associated with the booking will be entered into the Point of Sale Screen as a refund.

You can then refund the money by selecting the payment button on the screen or by selecting the applicable payment method on the keyboard.