General :: Making Unremovable App

I know making a real unremovable app is impossible, but I hope I'll be able to find a way to make an app harder to remove.I want to make some kind of parental protection app. it should be installed easily without much technical knowledge ( preferred that it will work on unrooted devices). the app should be hard to remove or disable by the phone user.who ever installed the app should be able to remove (probably with a password in the app settings).

I don't care if technical users will be able to easily remove the app.I also don't care if the users will know that the app is installed on their device.I guess the simplest solution will be to some how hide the app from the app drawer.I saw some where that Cerberus has that option but I guess it requires a root.

another solution might be if there is an option in the android os itself setting an admin password that will not allow the user to install or remove any apps without the password.