THIS IS THE SOLUTION!
After a few days and hours searching on the web without any answer I finally found a solution for the "Show me how" paper and toner waste print.
The solution is in fact very simple. What you have to do is "Lock the menus" so the users won't be able to print the "show me how" thing.
Process:
1.) connect the printer to a computer or a network.
2.) Access via the ip address to the printer settings.
3.) Once you access to the settings page you'll find 3 tabs. Click on "Settings" tab.
4.) Click in "security". Then under Configure security settings click "configure".
5.) Scroll down and look for Control Panel Access Lock option and select "Maximum Menu Lock".
That's it.
Once the users press any of the buttons on the printer there'll be a message saying "Locked Menu" and the waste of paper and toner will be finally solved.
Hope this helps future readers.