From the settings 'users' menu you can add and edit the people who have access to your admin system. Users can be set to 'admin', 'manager' or 'cashier' and can be active or inactive.
When adding or editing users you can set-up PIN's to allow users to lock/unlock the POS and quickly switch user i.e. log in/out:
In the add/edit user screen you can control name, email address, the type of user and also if the user account is active or inactive: