When you want to control who is booking a desk then your System Administrator can configure Engage to enforce bookings for your employees. For example, this could be used when an employee is waiting for clearance on a security check before they are allowed to make bookings.
You will find in Engage's configuration the Enforced Bookings Allowed check box and when checked this will turn on the feature. Also, note that there is a Booking Denied Message that will be displayed to the employee if they try and make a booking.
Also, your System Administrator will need to update the People Directory for the particular person. When the Booking Allowed drop-down is set to No, then this will stop the employee from making bookings.