How to Remove Network Authentication on Win7 laptop

Greetings,

My wife recently received a school laptop that was being retired (Thinkpad 3508). She does not work for that school district anymore, and before she left, she forgot to ask them to remove the network authentication from the computer. In essence, the computer boots, then after the ctrl-alt-delete, she is prompted to enter her old credentials. As she's not an employee anymore, it attempts to connect and then fails.

Since the computer is hers and she would like to use it at her next job, I'd like to remove that requirement from the computer and just have her login as a regular computer system user with no network authentication. I'm sure this is possible, but if anyone could help out I'd appreciate it. The unit doesn't have a CD drive so that hinders me from, say, putting in a linux boot dis, though I suppose I could make a thumbdrive Linux boot.

I look forward to links or some help on solving this.

Thanks!