"The 18th amendment was repealed by the Twenty-first Amendment to the United States Constitution. So one amendment is repealed by a second amendment. Amendments to the US Constitution can't be removed, they can only be "repealed" through the process of passing an additional amendment declaring them so."    Amendments to the Constitution, including those included in the Bll of Rights, are subject to the same actions which led to the repeal of prohibition. " 

There's little sense in debating the "democracy"/Constitutional Republic issue.  We are a republic (defined as a representive democracy), with representatives chosen by a democratic (rule by the people) process making the bulk of legislative/executive and judicial decisions for governance.  Your position, including accusing Mr. Quirk of treason, is not supported by any legitimate Constitutional authorities, judges or scholars.  

It's highly unlikely the Second Amendment would ever be repealed, but proposing it is not treason.....