You can uninstall or removes an installed libghc-mersenne-random-pure64- package itself from Ubuntu 14.04 LTS (Trusty Tahr) through the terminal,
$ sudo apt-get remove libghc-mersenne-random-pure64-
If you would like to remove libghc-mersenne-random-pure64- and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove libghc-mersenne-random-pure64-
If you use with purge options to libghc-mersenne-random-pure64- package all the configuration and dependent packages will be removed.
$ sudo apt-get purge libghc-mersenne-random-pure64-
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 libghc-mersenne-random-pure64-