In order for you to disable notification from CometChat Admin Panel.
Step 1:
Login to CometChat Admin Panel using your credentials.
Step 2:
From the Left side of the menu click on "General".
Step 3:
Search for "If yes, user offline notification will be displayed:", "If yes, user busy notification will be displayed:", "If yes, user online notification will be displayed:"
Step 4:
Change settings as per your requirement and click on "Update".