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