@mtv-jcil I would take suggestion of @brugman and maybe go 1 extra step (if my reasoning makes sense – see below).
I would check for something unique about the logged in user, and if it is not a user you want to see the cog, I would add an extra CSS Class to the body tag. Why?
This way… when doing the CSS to hide the cog, you can reference the body.(addclasshere) to the CSS Selector so that your agency users could still use it and just not other users.
Yes, not really necessary, but it could make sense to shave some service time off (over time). As I do use the cog at times when needing to add/edit the field group to save on going through Admin Menu > Find Group > etc. Some bigger (or older) sites some times take me a bit long to find it going through the multi-step approach.
Just my .02
