You can uninstall or removes an installed fusiondirectory-plugin-dhcp package itself from Ubuntu 16.04 LTS (Xenial Xerus) through the terminal,
$ sudo apt-get remove fusiondirectory-plugin-dhcp
If you would like to remove fusiondirectory-plugin-dhcp and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove fusiondirectory-plugin-dhcp
If you use with purge options to fusiondirectory-plugin-dhcp package all the configuration and dependent packages will be removed.
$ sudo apt-get purge fusiondirectory-plugin-dhcp
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 fusiondirectory-plugin-dhcp