This article explains how to turn off read receipts in WhatsApp, so that someone who contacts you won't know if and when you've read their messages. Instructions apply to WhatsApp for iPhone and Android.
How to turn off read receipts on WhatsApp
You can turn off read receipts on your iPhone in a few steps. This will disable the feature for all one-on-one chats.
Select Settings from the bottom menu.
Turn off Read Receipts.
