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