You can uninstall or removes an installed cyrus-pop3d package itself from Debian 7 (Wheezy) through the terminal,
$ sudo apt-get remove cyrus-pop3d
If you would like to remove cyrus-pop3d and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove cyrus-pop3d
If you use with purge options to cyrus-pop3d package all the configuration and dependent packages will be removed.
$ sudo apt-get purge cyrus-pop3d
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 cyrus-pop3d