I’ve not been keeping up with the latest hotness, but it seems that RBEnv is now the defacto way to mange Ruby versions. To remove RVM and use RBEnv instead:

 $ rvm implode

Then remove ~/.rvm manually and delete anything rvm-related in ~/.bashrc and ~/.bash_profile

Assuming we already have brew installed:

 $ brew install rbenv ruby-build

Add rbenv to your .bash_profile

 $ echo 'if which rbenv > /dev/null; then eval "$(rbenv init -)"; fi' >> ~/.bash_profile

Reload the bash profile

 $ source ~/.bash_profile

Install Ruby 2.2.1

 $ rbenv install 2.2.1

Set Ruby 2.2.1 as the systemwide default version (see rbenv docs)

 $ rbenv global 2.2.1

Check the version of Ruby:

 $ ruby -v

Sources: Stack Overflow and Rails guide to installing Ruby on Yosemite