Hello,
You can only change it if the Microsoft 365 account is also a personal Microsoft account. If it is a work or school account, that's a whole differen story.
To change, this is what you can do:
Go to Settings > Accounts > Your info
Click on Sign in with local user instead. follow the steps and finish the rest.
(If you don't see the "sign in with a local account instead option, click on "Stop signing into Microsoft apps automatically" first, then relaunch this page. )
Restart the computer (Do Not skip)
Go to Settings > Accounts > Your info
Click on Sign in with Microsoft account instead. follow the steps and finish the rest. Use the email address you want to use instead.
Restart the computer (Do Not skip)