There are no settings for this add-in.

You can see the green checkmark for the constraint parts in the Model browser.

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 can unload the plugin without uninstalling it by unchecking the "Loaded/Unloaded" checkbox associated with the plugin in the Autodesk® Inventor® Add-In Manager. You may have to restart Inventor to completely unload the application.

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, you can uninstall it from 'Control Panel/Programs and Features' (Windows 7/8.1/10), just as you would uninstall any other application from your system.

The source files for this app can be found on github: https://github.com/hjalte79/ShowFullyConstraint.

The green check icons disappear when the assembly is saved (and reappear when a change is made to the assembly).

This is done by design. The icons are saved to the file if they are not removed just before saving. That would mean that it would be impossible to remove them if you stop using this add-in.