Dual screen Mac High Sierra

Using my main monitor to view images full size and laptop to view Browser thumbs. Is there a way to eliminate the three buttons (close, shrink, full screen) from the top left of the screen - also the name of the session (top centre) I am viewing? Presumably, it is a MacOS issue, but hopefully, someone here has solved the problem.
You will notice that using Slideshow gives one a full screen without the extras, so it must be possible.