You can uninstall or removes an installed ext3-modules package itself from Debian 7 (Wheezy) through the terminal,
$ sudo apt-get remove ext3-modules
If you would like to remove ext3-modules and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove ext3-modules
If you use with purge options to ext3-modules package all the configuration and dependent packages will be removed.
$ sudo apt-get purge ext3-modules
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 ext3-modules