We have an NT4 server which is going to be decommissioned
and at one stage this was an active DNS server. There are
now two other DNS servers on the network which are
providing these services and are delivered to the clients
with DHCP leases. I have stopped and disabled the
Microsoft DNS Server. Can someone please advise if there
are any other steps required to completely remove this
DNS server or point me to some documentation which
outlines the recommended steps to remove a DNS server.

jcochran.nospam

You've stopped the service, so you've effectively removed it anyway.
Pull the plug.

Jeff