Uninstalling the app is not the solution.
Just uninstalling the app directly does not close your account. To delete the data, you must follow some steps.
This is the way to delete WhatsApp
1. Open WhatsApp on your iOS or Android phone first.
2. Tap on the three dots in the top right of your Android phone.
3. First click on your Account option.
4. Here you tap Delete My Account.
5. Enter the mobile number on the new page and click Delete My Account once again.
6. You have to give reasons before pressing the delete button.
7. Now tap Delete My Account once again.