In certain circumstances, you may wish to manually overlock the unit and restrict access to the customer, it's pretty simple. Here's how:
Navigate to Customers
Search for the customer you want to overlock and click on it
There are two ways to revoke the access
Option 1:
Scroll down to the bookings table
Click on the switch button in the Has access column
Option 2:
Click on the Actions button
Click on Revoke access for all bookings