DCPRMO

If it's a member server you don't need to run DCPromo.  Just go into the properties on the server itself and remove it from the domain.

DHCP will continue to function, but if you're doing to decommission the server, you should move that service to another server.

Without a DHCP server you'll have to assign static IPs, subnet masks, and default gateways to everything that currently uses DHCP.

DCPROMO is for Domain Controllers only. Since you state this is only a member server then all you need to do is disjoin it from the domain.

DHCP will not function as the server will no longer be trusted. Why not use your DC for DHCP instead?

So what is the consensus,  will DHCP still work after disjoining?  What are the steps to disjoin?

Microsoft's DHCP service does not require Active Directory to run - indeed, you don't even need a Microsoft DHCP server to operate a domain-based network,.

If the server is going to be shutdown, move your DHCP service to another server.

De-authorize the current DHCP service after you have everything ready on another server, then authorize the new DHCP service. Make sure computers are getting addresses from the new server. Then remove 2003 server from domain and shutdown. Monitor your network for awhile.

Krompton

The intention is physically keep the server in place until a replacement comes in (this may be a few months down the road) (the company was bought out so the entire Domain will change completely).
Currently, there are about 6 workstations total that are in a workgroup (not part of the domain) that will need to have DHCP or be setup statically?

If you are not operating a Domain there should be little issue with replacing the server.

Are there other IP devices in your network? For 6 or so devices, static IPs should be pretty easy to manage.

Beyond DHCP, what are you using this server for?

Cheers,
Krompton

Krompton:

The member server is part of a larger organization (company).  As mentioned earlier, the company was recently bought out so the actual hardware belongs to the new company, which is why it needs to be dis-joined.  

I have requested to have the router (Sonicwall) provide DHCP.  But for some reason, the POC seems to be stuck on having the server provide DHCP?

To my knowledge, there are no other IP related items.

"But for some reason, the POC seems to be stuck on having the server provide DHCP?"
You'd get more control with a Microsoft DHCP server than you would using DHCP from a firewall/router.  I'd do the same thing.

OK, so is there a clean way to disjoin the member server?

Would these steps be correct?

To remove a computer running Windows Server 2003 from the domain

    Click Start, point to Control Panel, and then click System.

    On the Computer Name tab, click Change.

    Under Member of, click Workgroup, and then type any name for the workgroup.

As Paulmacd said, that is the way to remove from a domain.

Also, to check for other IP addresses on your network you can use the below "FOR" command from a cmd window:

(1,1,254) = (StartingIP, increment, EndingIP). Change 192.168.10 to match your network. This is just a quick check and is not meant to replace keeping good records of devices on a network. Just a place to start.

FOR /L %i IN (1,1,254) DO ping -n 1 192.168.10.%i | FIND /i "Reply">>c:\Temp\ipaddresses.txt

Cheers,
Krompton

Most important was to create or assign a password to the administrator account to be able to access after restart.