The Archive Chat feature allows you to hide a conversation from your Chats screen and access it later, if needed. You can archive group 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.
For physical keyboard phones:
For touch screen phones:
The chat is now archived and will not appear on your Chats screen.
For physical keyboard phones:
For touch screen phones:
Archived chats will also reappear when you receive a new message in that conversation.
Learn how to use Archive Chat on: Android | iPhone | Windows Phone | Nokia S40 | BlackBerry | BlackBerry 10
Cheers,
WhatsApp Support Team