I am having difficulties trying to remove the back/home button from the action bar.
getActionBar().setDisplayShowHomeEnabled(false); //disable back button
This code work for me
For remove navigation bar
getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
For remove status bar
getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_FULLSCREEN);
ฺBut above code, it show again when you touch on screen, so if you want static state, combine this code.
getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
| View.SYSTEM_UI_FLAG_IMMERSIVE);