Deleting the Microsoft Authenticator app or transferring it to a new phone number will break the trust between Microsoft and your device, and you'll need to use one of your other configured MFA methods to reestablish that trust. If no other MFA methods are configured and you cannot sign in to your account, please call the CIT HelpDesk at 585-245-5588. They will verify your identity over the phone, and walk you through reestablishing a working MFA method.