reset_callbacks

# File activesupport/lib/active_support/callbacks.rb, line 530
      def reset_callbacks(symbol)
        callbacks = send("_#{symbol}_callbacks")

        ActiveSupport::DescendantsTracker.descendants(self).each do |target|
          chain = target.send("_#{symbol}_callbacks").dup
          callbacks.each { |c| chain.delete(c) }
          target.send("_#{symbol}_callbacks=", chain)
          target.__define_runner(symbol)
        end

        self.send("_#{symbol}_callbacks=", callbacks.dup.clear)

        __define_runner(symbol)
      end