unregister

# File actionpack/lib/action_dispatch/http/mime_type.rb, line 217
      def unregister(symbol)
        symbol = symbol.upcase
        mime = Mime.const_get(symbol)
        Mime.instance_eval { remove_const(symbol) }

        SET.delete_if { |v| v.eql?(mime) }
        LOOKUP.delete_if { |_,v| v.eql?(mime) }
        EXTENSION_LOOKUP.delete_if { |_,v| v.eql?(mime) }
      end