Follow These Simple Steps-
This is another major problem from many
users are suffering. They might have created
WhatsApp account or abort the installation.
Now, those people who have their number find
them on WhatsApp, send messages and never
got reply back.
Keep in mind, even if you change your SIM
card, your account will not automatically
gets deactivated, it will still available.
To delete your account permanently,
navigate to Settings >> Account >> Delete
Your Account. Enter your phone number and
you’ll be removed from WhatsApp.