Disable/Lock Safe Mode Boot

[AC Question]

Since the android 7 update no third party app works to lock safe mode. So now there is no program effectively locks files or programs because booting in safe mode allows anyone to remove all 3rd party apps like sure lock or a parental restriction app. So my question is how do you disable the ability to boot in safe mode to prevent someone from uninstalling a locking or parental restriction app. Specifically for and S7 active on at&t.