Need to restrict access to all admin pages, only allow front-end page access…

I decided to purchase your plugin membership, but I’m having a problem: I’m trying to offer a free signup (still requiring name/email/info) for users to access front-end pages/menu-items only.

I created an “admin” role, a “member” role, and a “stranger” role. To the “admins” I gave permission to all pages and menu-items, to the “member” role I gave permission to access only certain pages and menu-items, and to the “subscriber” role I gave access to only a front-page, etc.

My problem is that a new test “member” I created has access to the WP admin backend/dashboard. I only want “members” and “strangers” to have access to the front-end of the site at all times, with only a few manually selected “admins” getting access to the WP backend.

I’m not using WPMU for this site. I know there’s got to be an easy enough way to do this that I must be overlooking.

Any thoughts?