WhatsApp privacy settings: last seen, online, read receipts
This tutorial will show you step by step how to hide your “last seen” and “online” statuses and disable read receipts (blue ticks) on WhatsApp on Android.
Contents:
The steps on this page work for all Android phones, such as Samsung, Google, OnePlus, Motorola, Xiaomi, Nokia, Oppo, and all other Android phones.
How to hide your “last seen” and “online” statuses on WhatsApp
The “last seen” and “online” statuses tell you the last time your contacts used WhatsApp, or if they're online.
Steps
1. Open WhatsApp.
2. Tap on the menu button.
For some Android devices, the WhatsApp menu button is a physical button on your phone located at the bottom left or bottom right, and for some devices, the menu button is in the upper right corner of your phone's screen. The icon for the menu button will look different on different phones.

3. Tap on Settings.

4. Tap on Privacy.

5. Tap on Last seen and online.

6. Under “Who can see my last seen”, you select Nobody.

Your “last seen” status is now hidden.
7. Under “Who can see when I'm online”, you select Same as last seen.

Your “online” status is now hidden as well.
How to disable read receipts (blue ticks) on WhatsApp
Check marks will appear next to each message you send. The double blue check marks mean that the recipient has read your message.
Steps
1. Open WhatsApp.
2. Tap on the menu button.
For some Android devices, the WhatsApp menu button is a physical button on your phone located at the bottom left or bottom right, and for some devices, the menu button is in the upper right corner of your phone's screen. The icon for the menu button will look different on different phones.

3. Tap on Settings.

4. Tap on Privacy.

5. Tap on the toggle button next to Read receipts to turn it off.

The read receipts (blue ticks) are now disabled.
Read more articles about Android, WhatsApp
Related:
How to hide your last seen and online status on WhatsApp Web
References:
https://faq.whatsapp.com/3307102709559968/