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