How To Stop Whatsapp From Sharing Your Phone Number With Facebook
There are three ways by which you can stop Whatsapp from sharing the phone number with Facebook.
When you launch WhatsApp you will get a prompt to Agree to its new terms of service. You will find a checkbox and an Agree button. You will have to uncheck the box to opt out of the agreed terms.
Launch WhatsApp on your iPhone.
Tap Settings on the right bottom corner.
Tap the switch to disable Share My Account Info.
If you are concerned about the privacy issue, simply go ahead and uninstall Whatsapp. Well, you can try these Whatsapp Alternatives for iPhone.