The Archive Chat feature allows you to hide a conversation from your Chats screen and access it later, if needed. You can archive groups or individual chats to better organize your conversations.
Note: Using Archive Chat does not delete the chat or back it up to your SD card.
The chat is now archived and will not appear on your Chats screen.
Archived chats will also reappear when you receive a new message from that conversation.
Learn how to use Archive Chat on: iPhone | Windows Phone | Nokia S40 | BlackBerry | Nokia S60 | BlackBerry 10
Cheers,
WhatsApp Support Team