[Seeker]

Co-signer is one who supports you and will backup you if you cannot or don't make payments. Generally a co-signer does not have a physical CC as a co-signer. They are just a supporter... co-signer usually does not accumulate more debt.

That's was how I interpreted the question at first.

Owner is someone who has the account as owner (the "Primary" in CC terminology) and adds someone else to it (the co-owner). The co-owner in this case, may not be "authorized" to make changes, however since there's no debt on the card, she/he should be able to get themslves off of it.
Usually the "owner" must request the change...