There is a way to remove the user interface, but I'm not sure how. It involves modifying your files or something to that effect.
However, you can always take a screenshot, and then delete the extra stuff.
Do you have a scroll on your mouse? Use the scroll to zoom in and out. Or if you're using the RTS-setup, you can also use "R" and "F" to zoom-in and zoom-out. Those keys might be different, though, on other keyboards as I've noticed my version of the game has different hotkeys than most players.