a) make sure you know the local Administrator password for this server. Not the abc.local Admin password, but the local Administrator account password on this server. And then log into the server with the local Administrator account.
b) Right-click on My Computer, choose Properties, then the Computer Name tab (I am on an XP box right now, so the tab name in Win2K might be different)
c) click the Change button
d) you want to move the server to a Workgroup, so choose Workgroup, give it a name (like WORKGROUP), and click OK.
e) reboot
f) log in with the local Administrator account, then go back to the Computer Name tab, and choose Domain, and add it to your domain.
g) reboot.
That's it.