You can uninstall or removes an installed ldp-docbook-dsssl package itself from Ubuntu 14.04 LTS (Trusty Tahr) through the terminal,
$ sudo apt-get remove ldp-docbook-dsssl
If you would like to remove ldp-docbook-dsssl and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove ldp-docbook-dsssl
If you use with purge options to ldp-docbook-dsssl package all the configuration and dependent packages will be removed.
$ sudo apt-get purge ldp-docbook-dsssl
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 ldp-docbook-dsssl