How can I uninstall Ruby on Rails on Mac OS X?

I am following a tutorial about Ruby on Rails, and the tutorial got updated to a new version of Rails, so I can't follow it anymore because I have an older version.

I would like to start new and uninstall Ruby on Rails and any related software on my Mac OS X 10.5.8, and follow it from ground up. If anyone would be willing to help me uninstall Ruby and Ruby on Rails, it would be much appreciated.