Hello,
I would like to remove individual SmartThings devices from the Google Home App. Since this does not work in the Google App directly, I wanted to ask if there is another way to exclude the devices. Thank you very much in advance 
In the Classic app, go to Automation > Google or in the new app go to three bars in the upper left of screen, click on the settings cog, select connected services > Google.
At the top of either, deselect Allow Google Assistant to access all devices, scenes and routines. This will allow you to individually select devices to be used by Google Assistant.