Select the desired category of elements to remove duplicates under their classes whether model or annotation categories, then hit OK and a massage will show for the removed duplicated items.

The installer that ran when you downloaded this app/plug-in from Autodesk App Store will start installing the app/plug-in. OR, simply double-click the downloaded installer to install the app/plugin. 

You may need to restart the Autodesk product to activate the app/plug-in. 

To uninstall this plug-in, exit the Autodesk product if you are currently running it, simply rerun the installer, and select the "Uninstall" button. OR, click Control Panel > Programs > Programs and Features (Windows 7/8.1/10) and uninstall as you would any other application from your system.