I understand your concern. Since you are using Windows 10 Education edition, the option to switch to a local user may not be available. However, you can still change the email associated with your user account. Here are the steps to do so:
- Go to Settings > Accounts > Email & accounts.
- Under the "Accounts used by other apps" section, click on the email address you want to remove.
- Click on the "Remove" button and confirm the action.
- Click on the "Add an account" button and follow the prompts to add your personal email address.
- Once your personal email address is added, you can set it as the default email address for your user account by going to Settings > Accounts > Your Info and selecting your personal email address under the "Email address" section.
Please note that changing the email address associated with your user account may affect some applications that rely on your old email address for authentication. You may need to update the email address in those applications as well.
To avoid complications in the future however the reinstall option is the best way to go.
Depending on policies & configuration setting currently in place by your school's management of the device and the expiry of the education license you will not be able to configure or control some features and settings.
Hope this helps,