How do I get true full screen (no gray at the top) in my game tab?

I’m looking to have my game window take up absolutely the whole screen on a second window. ANYTHING that is not black I would like removed (see image), I just haven’t found how to do it yet.

You have to build the game.

That will always show in the editor / game Engine even in full screen.

** you’ll have to specify the full screen settings when you build the game in the Build options **