Windows 2000 server reconfiguration

I have a Windows 2000 server, running Active Directory in its own domain (I inherited this mess). I want to kill Active Directory for now, and move the server to the correct domain. Is there a way I can do this safely, or am I looking at the obligatory rebuild? The other domain is currently an NT 4.0 domain and we aren’t looking to migrate to Active Directory for quite some time.