You can uninstall or removes an installed ferm package itself from Debian 7 (Wheezy) through the terminal,
$ sudo apt-get remove ferm
If you would like to remove ferm and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove ferm
If you use with purge options to ferm package all the configuration and dependent packages will be removed.
$ sudo apt-get purge ferm
If you use purge options along with auto remove, will be removed everything regarding the package, It's really useful when you want to reinstall again.
$ sudo apt-get purge --auto-remove ferm