Microsoft Authenticator not restoring after changing to a new phone

I recently changed my mobile phone, and Microsoft Authenticator was not backed up on my old device. I no longer have access to the old Authenticator registration, and I’m unable to sign in because the MFA verification is still linked to my old phone.

This is urgent as I need access to my account.

Could you please advise me on how to reset/remove the old MFA/Authenticator registration so I can register Microsoft Authenticator on my new phone and regain access to my account?

I would appreciate your urgent assistance.