Hey, @dgs - there is an idea for this in our Ideas Portal. Please add your vote there!
https://ideas.ringcentral.com/ideas/ENTCOM-I-111

Currently, there is no way to delete a profile picture from the new RingCentral unified app on Windows, iOS and Android platforms. I'm running Version: 21.1.11.356 Web, 20.3.10.1872 Windows - and the only option that exists is to 'Add/Replace' a profile picture, so it is extremely strange that a simple 'Delete/Remove' function doesn't exist.