How do I prevent fields with Admin Only visibility from displaying on the front end?
There are a few code snippets on the Formidable Forms site that help you get started with a solution. The code snippet below will retrieve and hide all fields dynamically where you have their visibility set to Administrator.
https://gist.github.com/vfontjr/26edc40a382cfebd546a7dbb674636f5#file-dynamically-hide-admin-fields-front-end-php