How to disable installing from unknown sources?

Is there a way to disable the phone from installing apps from unknown sources? I know that it is possible by just going to. settings->security->unchceck "unknown resources" **But when kids install apps, a dialog appears:** By just tapping on settings, they can **Enable** it again and install the application. is there a way to disable it and the dialog won't come out or make it grey so it won't be clicked/tap it again? Without putting password on my Settings.