The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

WordNet (r) 3.0 (2006):

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

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "demobilize":
   break up, cast loose, deactivate, debrief, decommission,
   demilitarize, demob, detach, disarm, disband, discharge,
   disintegrate, dismiss, disorganize, dispel, disperse, dissolve,
   go bail for, go separate ways, grant bail to, let go, let go free,
   let loose, let off, let out, muster out, parole, part,
   part company, put on parole, reconvert, release, retire, scatter,
   separate, sheathe the sword, split up, unhand, withdraw