Source : Webster's Revised Unabridged Dictionary (1913)

Demobilize \De*mob"i*lize\, v. t. [Cf. F. d['e]mobiliser.]
   (Mil.)
   To disorganize, or disband and send home, as troops which
   have been mobilized.

Source : WordNet®

demobilize
     v 1: release from military service or remove from the active list
          of military service [syn: {inactivate}, {demobilise}]
          [ant: {call up}]
     2: retire from military service [syn: {demobilise}, {demob}]
        [ant: {mobilize}, {mobilize}]