One is by opening the Finder, then click Macintosh HD > Applications > Utilities > Terminal.
Step 1: There are three ways of opening Terminal on your Mac laptop. If you’re afraid of messing up your computer with Terminal, don’t worry – this trick is harmless and is a foolproof way of turning off your Mac laptop display without putting it to sleep mode or shutting down the entire computer. If your Mac laptop runs OS X 10.9 or newer, you can turn off your laptop display using a simple Terminal command. Use Terminal to turn off the display (Mac) If you’d like to wake up the display, simply press any key, click your mouse, or use the trackpad. Step 4: Your laptop display should turn off as soon as you press the Enter key.