When closing down your WhatsApp account it’s important to note that Publicly visible text/images often aren’t always properly deleted even when you have deleted your account. 

Deleting them manually before deleting the account itself is recommended. If you signed up for WhatsApp using a third-party login such as Facebook or Twitter, you should revoke all access from WhatsApp. 

To close your WhatsApp account, go to the main menu, Settings, Account, and choose the last option (Delete my account) the. delete the app from your phone.