Just copy paste these commands as they are in a new Terminal.

cd ~
rm -rf .rbenv/
git clone git://github.com/sstephenson/rbenv.git .rbenv
echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bashrc
echo 'eval "$(rbenv init -)"' >> ~/.bashrc
git clone git://github.com/sstephenson/ruby-build.git ~/.rbenv/plugins/ruby-build
source ~/.bashrc

#rbenv #ruby