yes it is, that means you have to password protect the uninstallation app(either the main settings it self or the uninstalling app you've downloaded) you also need to protect the "play store" so that they cant download the uninstallation app, the internet connection (3g/4g/wifi) and the cms... that means when you open the uninstallation app you need to put password in it first. i tried it many times and it password protect the uninstallation. not sure why its not working to you

I got your point, protect the uninstallation app's to block other user launch the uninstallation page~