Solution:
Step 1: Login to your WordPress Admin
Step 2: Click on “WhatsApp Care” from the admin menu.
Step 3: Click on “Basic Settings” tab.
Step 4: Find “Custom CSS” option.
Step 5: Copy following the code and paste into “Custom CSS”
.wcc-popup__header { background-image: none; }
Step 6: Click on “Save” button.