The Collaborative International Dictionary of English v.0.48:

Unhang \Un*hang"\, v. t. [1st pref. un- + hang.]
   [1913 Webster]
   1. To divest or strip of hangings; to remove the hangings, as
      a room.
      [1913 Webster]

   2. To remove (something hanging or swinging) from that which
      supports it; as, to unhang a gate.
      [1913 Webster]