Sorry, you can't change the name. You have to set up an entirely new domain rooted at the correct domain name system (DNS) domain name. Then you must migrate the accounts (users, groups, computers) to the new domain using either Active Directory Migration Tool (ADMT) from the Microsoft web site or a third party migration tool.
I'm judging from your UPN that you work in a school district. You might have hundreds or thousands of accounts to migrate. The SIDHistory feature will maintain user access to resources, but you'll have issues with retaining passwords and local profiles. Be sure to test your migration scenario several times before trying it in production. If you decide to use a third party tool, be prepared to spend some money.
This was first published in February 2001