Short video:

While adding a co-worker into your account, you will have the option of making the co-worker an Administrator, a Supervisor, or a User.

If you need to make an already existing user into an Admin or a Supervisor, you can click on the 'Edit' icon (setting like icon) on the user in the 'Co-workers and Groups' page and select 'Admin', ‘Supervisor’ from the dropdown. 

NOTE: Admins will have a crown icon near their name, Supervisors will have a shield icon. This should help you differentiate if a co-worker is an Admin, Supervisor, or a regular user.

To control the page-level permissions for the Supervisors and users please refer to the article here.