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