This article defines you how to disable entirely your built in speakers of window. Simply,Open startup button on you PC, go to your Device Settings, Click on Devices and open Device window there.  Now click on Bluetooth & other devices, and go to  Sound settings. Select a device to modify its settings.You will see a Speakers icon with white check along with green background, Double click on Speaker icon. Doing so, open speaker Properties window. If you are running this speaker currently, you will see a sound meter on the right side of the window. Click on the Device Usage option and drop down the tab and choose this option ” Don’t use this device (Disable). Now click and save settings.

If you are searching this same setting on Laptop, simply go to Control Panel, open Hardware & sound, and click on sounds. You will see a little screen with different options, you will see Speakers/headphones. Now Choose one option and open its properties. Open General tab, and at the end of this screen, you will see device usage Button, drop down the tab and choose Don’t use this device (Disable), option there.