You can uninstall or removes an installed libdebconfclient0-udeb package itself from Debian 8 (Jessie) through the terminal,
$ sudo apt-get remove libdebconfclient0-udeb
If you would like to remove libdebconfclient0-udeb and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove libdebconfclient0-udeb
If you use with purge options to libdebconfclient0-udeb package all the configuration and dependent packages will be removed.
$ sudo apt-get purge libdebconfclient0-udeb
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 libdebconfclient0-udeb