Three Roles
Owner
The person who created the circle. Full control over settings, members, and the circle itself. Can delete the circle.
Admin
Promoted by the owner. Can manage members (accept/reject requests, remove people), but cannot change circle settings or delete the circle.
Member
Standard membership. Can post submissions, react, comment, and invite others (if the circle allows invites).
Managing Members
The owner can promote members to admin or demote admins back to regular members. The members page shows everyone with their role and join date.