If you installed Windows with a Microsoft account but would like to use it with a standalone account, you can do this using System Preferences.
Deleting a Microsoft account in Settings:
- Open “Settings” and go to “Accounts”.
- Open the “Your details” item.
- Under “Account settings”, click on “Log in with local account instead”.
- Confirm the switch to the local account by clicking “Next”.
- Enter a PIN or password to confirm.
- Enter the username and password.
- Press “Next”.