NT has no safe mode.
When you get to the screen where you hit CTRL-ALT-DEL, there should be a pull down after the username and password that allows you to select the domain to boot from. There should be two domains listed, the larger NT domain, and a domain which is simply the name of the computer itself. Change this to the name of the computer itself, and then log in as administrator (you said you had the admin info, right?).
Once you are on the desktop, right click "Network Neighborhood" and then click on "Properties". Got to the "Identification" tab and hit the "Change" button. Click the radio button to change from whatever domain you are attached to and give it some workgroup name (make something up). You may have to enter the administrator's username and password again at this point. When it's done, it will prompt you for a reboot. After rebooting, you should no longer be attached to the domain.
Joe