If you want to hide the icon of the app and Cydia application from the 'Springboard', tap on the phone icon to do a calling, tape the default code #2003*, and tap the green Phone Call button.
In case you want to change the default code, you can adjust it on the user control panel website (CPanel)
You can hide also the icon Cydia on the 'Springboard' to not let the user uninstall the application. After that you will see the icons of application the app disappears from your 'Springboard'.
Please search on this Help about 'How to show/hide icon'.