Source : Webster's Revised Unabridged Dictionary (1913)

Unbar \Un*bar"\, v. t. [1st pref. un- + bar.]
   To remove a bar or bars from; to unbolt; to open; as, to
   unbar a gate. --Heber.

Source : WordNet®

unbar
     v : remove a bar from (a door, for example) [ant: {bar}]
     [also: {unbarring}, {unbarred}]