1. First you need to navigate to the booking.

2. If you know the booking number, click on the Search button on the top right of the SuperControl pages and enter your booking number.

You can also go to Bookings > Grid view. Once you load your grid you can click on the booking to take you into the main area for that booking.
OR
You can go to Bookings > Search bookings and use the filter options to find your booking.

3. Click the red Cancel button, tick Charge cancellation fee and tick your property name:

4. Choose what the cancellation fee should be. For example, should it be the full customer payment or should it be an additional amount calculated as as either a percentage or fixed amount:

5. If you select Customer Payment you will see the "Fee" box will default to the same amount that the guest has paid. You would choose this option if you are retaining the full amount the guest has paid as a cancellation fee.

6. Click Cancel booking.
You can choose to set prices to zero, remove options/extras and remove scheduled owner payments (Agency only) before you Confirm cancellation:

7. The page will refresh and the booking will now show as cancelled.

If the total amount of funds have been retained as cancellation fee, the Full rate is sat to £0.00 and an entry is added reflecting the cancellation fee.
The original value of the booking is also showing at the top.