Disable profile pictures

I am trying to disable the end-user from being able to change their profile picture. Reason being I am going to be using Oauth to determine their pfp. Even if I disable their ability to UPLOAD a profile picture, they still get the option to change it back to the unselected profile picture which is just their first letter.

I know I could probably hide the selector with CSS, but I don’t want users who are smart enough to be able to change their profile picture anyways.

Basically I am looking to disable system assigned profile pictures