how to remove a PPA cleanly?

Mon Feb 22 06:59:45 UTC 2010

* Archish <archish.rs at gmail.com> [2010-02-22 14:41 +0800]:
> I have been testing few things by adding PPA and the system has become
> unstable now.
> Is there any simple way to completely remove the installed software
> and its new dependency added via the PPA?

System > Administration > Computer Janitor

> My aim is to restore the dependent files version to the old ubuntu
> default version.