This feature was rolled out to first users a while ago and now it is expanding to more devices. It adds an optional Archived button on top of your conversation list. From there you can access all your archived conversations.
Alternatively, you can go to chat settings and turn the "Keep chats archived" toggle off to make it disappear.
- 📲 WhatsApp is a popular messenger app by Facebook.
- 📲 WhatsApp is also available in Beta and you can opt-in as a tester via Google Play.