Its always going to show that it is there.
You want to Show only the one screen then just goto the multiple screens tab and set it to the screen you have. So Screen 2 is my TV but Screen 1 is just the other port on my GFX card. ( Forgot to mention this part sorry)
https://puu.sh/suNIZ/36f63fd378.png
Disabling it in device manager is just extra precaution.