product advice - no reset button needed, parental control

So one simple solution would be to put the wifi router in a locked room with no access and only with someone with the key. If the master bed room doesn't have a lock, put on on and put the router in here. 

Most all business and home class routers have a reset button for in case of someone forgets all the user configurations and configured router and wifi passwords, the system can be reset and re-setup. Also used as a troubleshooting step where needed. This is industry wide. 

Most all home class routers have some form of remote control configuration, though some are limited to mobile apps that don't have advanced configurations as seen on the routers web page, so keep this in mind. NG has removed the web based remote web page control for security reasons so you might find other router mfrs that may support this...

Mobile apps for routers can have parental controls and security controls as well. NG has some that are subscription based. There has to be someone with email and cell phone code access to get access to the mobile app controls here so if the child doesn't have this, then this could be of some help.

One could also do more parenting and discipline any offending events with the child as well. I.e. removing internet devices as a disciplinary action.