Every time package is removed via `apt-get remove`, a tiny piece of its configuration can be kept in your system. If you ever need to reinstall the package, this information can be re-used. These packages has status ‘rc’ in the output of `dpkg -l`. But if you want to keep your system tidy and clean, you may want them to be removed.
The miraculous command is
dpkg -l | egrep ^r | cut -d ‘ ‘ -f 3 | xargs apt-get remove –purge -y