Cannot get Challenge Code to sign into Windows 11 PC

My wife is a teacher and her parents surprised her with a new PC (Windows 11) to do her school work on.

When the tech installed it, he suggested she use an authenticator to sign into the PC cause it would make it more secure since she would be working with students personal info. They thought it was a good idea so they said yes and he set up the sign in using her work email. I believe it’s Thales Safenet, where she enters her email address, a challenge code is then sent to her phone, and she must enter that code into the PC in order to sign in.

When her employer offered her a new contract in May, she informed them she would not be returning. To this they immediately cancelled her work email and told her she was no longer needed. Unfortunately, by deleting her email, she now cannot gain access to the challenge code since it was registered with her work email address. When I called the schools IT dept, their attitude was she doesnt work here so we cant help you. When I called the tech who installed it, he told me the only thing that can be done is I have to pay him to come reformat the PC and start over.

Is there any way to by pass this login or do I really have to start from scratch and loose years of my wifes lesson plans? It has the option to sign in with a different user, but the tech never added one. I tried to add a user based on comments I found on Google, but no luck.