Removing Access To 'file Editor' For Vendor Admins

I am setting up a multi vendor store and am working on editing the permissions for my vendors. I like the built in access/current permissions EXCEPT that from the dashboard they can access the “Design”> FILE EDITOR.

I absolutely can not have my vendors having access to the file editor, with this access they can completely break my site by changing the css. Is there any way I can remove this altogether from the Vendor Admin dashboard.

From my understanding they can upload their files manually when adding a product and that will serve me just fine!