Getting rid of a chat person from the Smart Chat Bar in Zoho Mail

Getting rid of a chat person from the Smart Chat Bar in Zoho Mail

In our group of 5 collaborators we have ONE individual whose chat status shows up at the far right of the Smart Chat tool bar in Zoho Mail.  You can see in the attachment "Catherine" with the green available status.  How do we get rid of that? Her status fluctuates from "Available" to "Invisible" at random seconds apart from each other when she is away sometimes with pop ups and it is annoying as hell.  No one else in our team shows up on the tool bar in that area.  Is it a setting on her end, the OS she's using.  Whoever can tell me how to GET THAT GONE will be an e-God!  ::))