You can uninstall or removes an installed libghc-mmap-dev-0.5.7-96941 package itself from Debian 7 (Wheezy) through the terminal,
$ sudo apt-get remove libghc-mmap-dev-0.5.7-96941
If you would like to remove libghc-mmap-dev-0.5.7-96941 and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove libghc-mmap-dev-0.5.7-96941
If you use with purge options to libghc-mmap-dev-0.5.7-96941 package all the configuration and dependent packages will be removed.
$ sudo apt-get purge libghc-mmap-dev-0.5.7-96941
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-mmap-dev-0.5.7-96941