I’m sorry you’re dealing with this. Since the old Microsoft account was compromised and you can no longer verify it, you will not be able to replace it with the new account from the Windows sign-in screen.
You can completely reset the computer:
- On the sign-in screen, hold Shift while selecting Power > Restart.
- Select Troubleshoot > Reset this PC.
- Choose Remove everything if you want the computer returned to a fresh setup state.
- Select Cloud download or Local reinstall, then follow the prompts.
- After the reset, Windows will start from the initial setup screen, where you can sign in with your new Microsoft account.
Important: “Remove everything” deletes personal files, installed apps, accounts, and settings. If device encryption is enabled, Windows may request the BitLocker recovery key. Because that key may be stored in the compromised account, check whether you saved or printed it elsewhere before starting.