Software :: Deleting User Account (Set As Default) Via Unix

I have a Mac computer at home that automatically logs in to my daughters user account. Apparently, there is an automatic log-in in her account that has conflicts because whenever the computer is turned on, after the gray apple screen, the screen turns totally blue. I have tried booting up in safe boot (pressing shift key at startup)and get the following message:
darwin/BSD (Laurens-computer.local) (console)
login:

After typing any login, I get a line for typing password but nothing types in the line of password and I keep getting a fast message of incorrect password and the screen goes back to blue and then back to the same darwin line. I have an administrator account on this computer and no combination of logins and passwords seem to work. I have also started the computer with command key + s key and gets into single user mode and is in the root. From there, I do not know how to delete her user account to eliminate the problem as I am not able to get into the computer bypassing her automatic log-in. I do not have any startup disks for this computer as it was donated as a surplus from the school. It is a G3 operating on Mac OS X and I am not sure if the version is 10.3