I used this script to install erlang.
but later I found out https://github.com/yrashk/kerl. My question is how to remove old version of erlang in a clean way.
Usually there are just four folders affected by the installation:
bin executables:
/usr/local/bin/ct_run
/usr/local/bin/dialyzer
/usr/local/bin/epmd
/usr/local/bin/erl
/usr/local/bin/erl_call
/usr/local/bin/erlc
/usr/local/bin/escript
/usr/local/bin/run_erl
/usr/local/bin/snmpc
/usr/local/bin/to_erl
/usr/local/bin/typer
configuration file and epmd starting script:
/usr/local/etc/man.d/erlang.conf
/usr/local/etc/rc.d/epmd
a lib folder containing Erlang libraries:
/usr/local/lib/erlang/*
and the documentation:
/usr/local/share/doc/erlang/
They may be located slightly differently on your system, but you can always use something like find . -type d -name erlang to locate them.
That script you mentioned also installs some dependencies. You may use standard apt-get command to deinstall if needed, but they probably will be required by the Erlang installed by kerl anyway.