The appointment of an elder is “approved” by the Watchtower Society, registered with the Watchtower Society as a legal entity, but the appointment of an elder or removal is still done by the local congregation.
That is like saying that when Microsoft buys out another company, the person in the finance department who writes the check is responsible for the acquisition, instead of the executives. The congregation announces whatever appointments and deletions the WTS approves and tells them to announce. They only make recommendations and announce them after they are approved. WTS has the final word.