If you wish to add WhatsApp support for your customer, Follow this step to enable it. 

Step 1: Go to Business Profile. 

Step 2: At the bottom add a WhatsApp Support number with Country code (Don’t add + Symbol)

Strep 3: Restart the Application and you will see the WhatsApp support button on the Home page. If you scroll the page that button will expand to get attention. 

If you wish to remove this button, Simply remove the WhatsApp number from your Business Profile.