To uninstall designate-zone-manager just follow these instructions.
/debian/stretch/main///install/index.html OpenStack DNS as a Service - zone manager Debian 9.0 net 1:3.0.0-4
sudo apt-get remove designate-zone-manager
Which will remove just the designate-zone-manager package itself.
sudo apt-get remove --auto-remove designate-zone-manager
This will remove the designate-zone-manager package and any other dependant packages which are no longer needed.
If you also want to delete your local/config files for designate-zone-manager then this will work.
sudo apt-get purge designate-zone-manager
Or similarly, like this designate-zone-manager
sudo apt-get purge --auto-remove designate-zone-manager
|Description||OpenStack DNS as a Service - zone manager|