Reinstall Ruby on OS X

It sounds like what you probably want to do is clear out all your globally installed gems in the system Ruby. This can be done by running the following:

sudo rm -rf /Library/Ruby/Gems/*

This will leave all the gems that come with OS X (which is a good thing, since some apps may assume they're installed).

As macarthy said, I also highly recommend using a Ruby version manager (e.g. rbenv or RVM) to more easily install, remove, and manage Ruby versions.

My suggestion would be to forget about what you have and use RVM

• https://rvm.io

you can basically ignore what you have installed then.