Stop teen from reinstalling apps after they are deleted

My son installed an app on his phone after I approved it through my parental permission. Upon learning more about the app, I do not want him to have it. If I delete it, he can just install it again by going to the app store. I realize I can change the settings so that he cannot access the app store at all, but really, I just want to make it so he can't install that same app without having to go through my parent permission first. Why does Apple do it this way? Obviously, there will be many circumstances where an app is installed, identified as inappropriate, and then deleted. There should be an easy way to keep deleted apps off your child's phone. Any ideas? And yes, I realize I can ground him and take his phone away if he abuses the privilege, but sometimes prevention is just the best course of action.