Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hello Aditya_J, my name is Emmanuel. I'll be more than happy to assist you today!
I completely understand your concern about the security of your Microsoft account by only having a single option to be able to sign using the authenticator app. If you want to only use the authenticator app when signing in, you can go to the ADVANCED SECURITY SETTINGS by logging into your Microsoft account using this link https://account.microsoft.com/ then go to SECURITY > click GET STARTED under ADVANCED SECURITY OPTIONS then from there, you would be able to set to use TWO STEPS VERIFICATION to be able to sign in to your account. If I am not mistaken, you can only remove the email and SMS option from there. Here is the quick access link https://account.live.com/proofs/manage/additional
Please be extra careful when you set your sign in preference of using the authenticator app only.
I hope this information answers your question.
Let me know if this works for you.