NAME CHANGED BY HOST

I gave permission to the one hosting regular meetings to have the ability to change my name. I would like to take this back, as they have changed my name to a name I would rather not have. How do I get back my control of changing my own name without them doing this remotely?

I have asked them to change my name on their screen, but they haven't done so. So, to exert more control on my ability to change my own name, please give me directions as to how to do this.

Thank you