The Collaborative International Dictionary of English v.0.48:
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. [1913 Webster]WordNet (r) 3.0 (2006):
unbar v 1: remove a bar from (a door) [ant: bar]