Open ADSI edit.
Configuration-> Services- > NetServices
Checked the properties of: CN=DhcpRoot
Then edited this attribute: dhcpServers
There was one server listed in there:
This was the one that seemed to be left hanging around.
Took a note of the settings just incase then deleted it and clicked “OK” to apply the settings.
Checked the DHCP MMC snapin under the “Manage Authorised servers” and its gone! harrah.