How Do You Reset A Chromecast without using the Google Home app. You do this by using the reset button on the Google Chromecast itself. This way works even if the Google Chromecast is not connected to WiFi or is not showing up in the Google Home app.
First make sure the Google Chromecast is plugged into your TV and connected to a power source. The Google Chromecast needs to be powered on. Now look for the button on the side or back of the Google Chromecast. The button is in a place depending on the model of the Google Chromecast.. Hold this button for about 20 to 25 seconds. The LED indicator light on the Google Chromecast will stay solid at first then it will start blinking. Keep holding the button until the light on the Google Chromecast starts flashing fast and the TV screen goes blank.
Let go of the button at that point. The Google Chromecast will restart by itself. Go back, to how it was when you first got it. This means it forgets all the WiFi networks it was connected to all the Google accounts that were linked to it and any custom settings you made. After the Google Chromecast is reset you can set it up again from the beginning using the Google Home app on your phone or tablet.