Facebook – How to get the count of messages with someone in Facebook

If you are friends with the person you want to make admin, go to your companies page and click the 'Edit Page' button under your page's profile picture. On that page in the right column near the bottom it will list 'Admins' with an 'Add' link. This will give you your personal friends list which you can search on and select people to become admins.

I've found that friends that disable their own account still appear (only to you) in your friends list and you can unfriend them; these friends can re-activate their account whenever they like. However if Facebook has disabled the account due to someone reporting it as a fake name or account, then they no longer appear in your friends list. If the person eventually clears this up with Facebook (e.g. by sending Facebook a copy of their ID) then Facebook may re-enable their account and they will re-appear on your friends list.

I agree with you that you should still be able to unfriend these people, but Facebook does not appear to provide a way to do that (other than deleting your account).