Hide WhatsApp last seen in official App.
Finally in the Android version of WhatsApp,one can hide last seen.
But for that you need to download the official App from their website. As the Play Store version is still the old version.
NOTE: Goto Settings->Account->Privacy to access the last seen option.
For your easy navigation, the download page; click here.
Once downloaded, you can install and replace the old App. Not to worry about your chats, as they will be there. But for safety, backup your chat.
Enjoy hiding last seen. Cheers!