To install the Google Earth Plug-in, browse to any page in which the plug-in is included (e.g. Google Earth API site).
Your browser will likely ask for permission before installing the plug-in. Click through to allow installation. Once the plugin is installed, you may need to refresh the page before the plug-in displays correctly.To verify that you have the Google Earth Plug-in installed, you can visit the Plug-in Homepage and check out the top, right corner. If the plug-in is installed, you should see this message:
Congratulations, you already have the Google Earth Plug-in installed! (Version...)
To uninstall the Google Earth Plug-in on Windows, select Start > Programs (or All Programs) > Google Earth > Uninstall Google Earth Plug-in.
You can uninstall the plug-in from Mac OS X by dragging the file /Library/Internet Plug-ins/Google Earth Web Plug-in.plugin to the trash before restarting your browser.