How to disable backend modules such as LOGGED-IN USERS or RSFIREWALL! CONTROL PANEL MODULE ?
You need to go in module manager. By default it shows the Site Modules, you need to filter to show the Administrator modules. You can disable them like the Site modules.
Be aware though to not hide any useful modules, like the Admin Menu, which might make you suffer then to navigate and find your way back to the module manager to re-enable it.