You can uninstall or removes an installed fat-modules-3.2.0-4-sb1-bcm912 package itself from Debian 7 (Wheezy) through the terminal,
$ sudo apt-get remove fat-modules-3.2.0-4-sb1-bcm912
If you would like to remove fat-modules-3.2.0-4-sb1-bcm912 and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove fat-modules-3.2.0-4-sb1-bcm912
If you use with purge options to fat-modules-3.2.0-4-sb1-bcm912 package all the configuration and dependent packages will be removed.
$ sudo apt-get purge fat-modules-3.2.0-4-sb1-bcm912
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 fat-modules-3.2.0-4-sb1-bcm912