If you want to increase tighter control on cancelling bookings, you can enable the option to allow only manager/owners the ability to cancel.
This can help with preventing staff from cancelling a large party booking without enforcing any cancellation policies you may have.
To change the settings so that only the manager/owner can cancel customer bookings you will need to firstly open the settings page of your simpleERB account.
Under advanced settings you will find the page titled staff. Once in the staff page you will see a few yellow boxes at the top.
The second tick box once selected, stops anyone not logged in as a manager or owner from cancelling bookings. You can enable/disable this at anytime.
When you are then logged in as a wait staff user, you will see from the individual booking place screenshot below (circled) that a note advises this can't be cancelled.