I'd like to be able to do this to limit the posibility of theft.
The only reason i can think of to have the button is for
Cash drawer checks and end of day. Both of which are done by management/supervisors.
You need to disable 'Open cash drawer without making a sale' checkbox for Cashier access group:
1. Go to Backoffice --> Employees --> Access rights
2. Select group in which you need to disable this right.
3. Disable the 'Open cash drawer without making a sale' checkbox.