This simple tutorial will show you how to purge packages that have already been removed with apt. In Ubuntu Linux when a package is uninstalled, the configuration files are left on the system. Purging a package will get rid of these configuration files to free disk space and keep system clean.
How to Purge packages:
First launch a terminal window from the dash or press Ctrl+Alt+T. Copy and paste this command into terminal and hit enter to check out packages that were removed but not purged:
sudo aptitude search '~c'
If aptitude not installed, run this to install it first:
sudo apt-get install aptitude
Then you can run this to purge them if you want:
sudo aptitude purge '~c'