Uninstalling ferret from source

I installed ferret from a tarball rather than gem install. Per the
README I
installed from the extracted directory via;

$ rake ext
$ ruby setup.rb config
$ ruby setup.rb setup
$ ruby setup.rb install

I’m now trying to uninstall but there are no instructions on how (either
in
the README or via “ruby setup.rb --help”).
How can I do this?

Much Thanks,
John