You can uninstall or removes an installed libgconfmm-2.6-1c2 package itself from Debian 8 (Jessie) through the terminal,
$ sudo apt-get remove libgconfmm-2.6-1c2
If you would like to remove libgconfmm-2.6-1c2 and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove libgconfmm-2.6-1c2
If you use with purge options to libgconfmm-2.6-1c2 package all the configuration and dependent packages will be removed.
$ sudo apt-get purge libgconfmm-2.6-1c2
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 libgconfmm-2.6-1c2