$ sudo apt-get remove ftpd-ssl 

Uninstall ftpd-ssl including dependent package

If you would like to remove ftpd-ssl and it's dependent packages which are no longer needed from Ubuntu,

$ sudo apt-get remove --auto-remove ftpd-ssl 

Use Purging ftpd-ssl

If you use with purge options to ftpd-ssl package all the configuration and dependent packages will be removed.

$ sudo apt-get purge ftpd-ssl 

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 ftpd-ssl 

See Also,