Hello,
If you do a righ-click on the DLP addon .ico you should be able to hide it pressing "hide in chrome menu".
In case that's not working, I would recommend to reinstall the agent with the Chrome closed to ensure the DLP addon for Chrome is correctly installed.
Anyway, if the end-user opens the Addons tab will see that the DLP addon is installed. Won't be able to uninstall it though.
Cheers,
Morgado