crwdns2933897:0crwdne2933897:0

How do you release the lens when the release button fails?

How do you take of a lens from the body of Canon Revel T1I camera when the release button fails to work? I've tried turning it several times and nothing works.

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2853045:0crwdne2853045:0 crwdns2853046:0crwdne2853046:0
crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0