title: Remove old built erlang from ubuntu
body: <p>I used this script to install erlang.</p>
  
  <p><a href="https://gist.githubusercontent.com/bryanhunter/10380945/raw/b4edf4c6fd39c604392a96ce6ff21953ff941e51/build-erlang-17.0.sh" rel="nofollow">https://gist.githubusercontent.com/bryanhunter/10380945/raw/b4edf4c6fd39c604392a96ce6ff21953ff941e51/build-erlang-17.0.sh</a></p>
  
  <p>but later I found out <a href="https://github.com/yrashk/kerl" rel="nofollow">https://github.com/yrashk/kerl</a>. My question is how to remove old version of erlang in a clean way.</p>