How to show 404 whenever/wherever I want

That code does't work for me. The whole syntax
return redirect()->to('/wherever');
is not working for me, at least not in that controller. But even if it did wouldn't it just redirect to /errors/nodata ??
I don't want to redirect though. I just want to show 404 page not found with the uri they were trying to access.

Scenario: They are an unauthorized user probing through my site, theres a url called /edit_products - that should only be viewable by admins.
If they are unauthorized as an admin they see 404 on that link.

You can see things I made with codeigniter here: itart.pro its not overly impressive as I have very little time to learn.