In order to manage web setting related to "Who's Online List" please follow below steps:
Login to CometChat Admin Panel.
From left side menu, click on "Settings->General"
search for "In Who`s Online list, for guests:". Change setting as per your requirement.
search for "For logged in users:". Do your respective Changes. Change setting as per your requirement
Click on "Update" button
Click on "Clear Cache" from the left side menu.
Clear Your Browser Cache.