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