D&C 81

 Frederick G. Williams was instructed - 

"...hearken to the calling wherewith you are called, even to be a high priest in my church, and a counselor unto my servant Joseph Smith, Jun.;

2 Unto whom I have given the keys of the kingdom, which belong always unto the Presidency of the High Priesthood..."  (Doctrine and Covenants 81:1–2)

Obviously, Joseph Smith held the keys of the kingdom.  But consequently, as a united quorum of the First Presidency, the quorum administered those keys.  That is why, in my mind, if a quorum president is released, the entire presidency is released.