An incorrect badge count on the WhatsApp icon is usually caused by an issue with your phone. Please try these troubleshooting steps to reset it:

• Ask someone to send you a new WhatsApp message. This should automatically refresh the message count.
• Tap and hold on the WhatsApp icon and drag it to the trash can icon (usually located on the top of the screen), then drag a new WhatsApp icon out of your app drawer into your home screen.
• Uninstall WhatsApp. Go to Settings > Device > Applications > Application manager > More > Show system apps > BadgeProvider > Storage (path may vary depending on your phone) or to your badge count app, tap Clear Data, and then re-install WhatsApp.
• Go to Settings > System > Developer options and make sure Do not keep activities is turned off. If you do not have developer options, skip this.
• Go to Settings > Device > Applications > Application manager > WhatsApp > Storage and tap Clear Data. You will have to reverify your phone number next time you open WhatsApp.

Badge count is a notification functionality provided by your launcher and is not a function of WhatsApp. If you continue to experience issues, please contact your phone's manufacturer.

Find out how to get badge count on your app here.