How to Turn off a Chromebook Screen When Connected to an External Display Joe Fedewa | Google Hooking your Chromebook up to an external display is a great way to be more productive. With a Bluetooth mouse and keyboard, you’ve got a desktop experience. The Chromebook display may seem redundant in this case, so you can turn it off. There are two ways to use a Chromebook with an external display. The extra display can be a secondary screen independent of the Chromebook display, or you can mirror your Chromebook’s display. RELATED: Next, go to the “Device” section and select “Displays.”