if its a iPad go to settings and press on ‘Restrictions’ and make a password.
i am not sure if you can block wifi but you can block ‘safari’ – the internet app.
you can also block anything including the camera (camera was just a random example)
to unblock it all you need to do is go back to settings and press on restrictions, type in the password and click on whatever you want to restrict
Someone ‘donated’ money to my school to buy 30 iPads and they are all restricted like that.
the only way to get around it is if you know the password (btw – i know the password to the ipads in school even after they have changed it countless times…)