Found a hack to Turn off ChromeCast. Tell me if there was an easier way, but never found one.
I wanted to turn off all items in my living room, plus chromecast tv.
To Do this:
1: create a Virtual Outlet
2: On the existing switch to turn off everything I added an action to Turn On and then Turn Off the virtual outlet*
3: Here is the hack, in google home app, I made a Automation to Turn off Chromecast when the outlets goes off.
*The reason I Turn on and off the outlet is due to the limitations of google home having only 1 starter.