WhatsApp's current version allows you to send messages that disappear after seven days. This might change soon as WhatsApp is testing a feature where you can get your sent messages to disappear after 24 hours.
There's also an improved version of the archive chats feature coming to WhatsApp very soon.
The Current Situation With WhatsApp's Disappearing Messages
In the current WhatsApp version, you don't get to select the time period after which your messages should disappear. When you open the disappearing messages menu, the only option you see is whether to enable or disable the feature.
WhatsApp, by default, makes your messages disappear after seven days once the feature is enabled. This time-frame isn't editable at the moment.
We believe WhatsApp does this so that you have enough time to recover messages, if any. Seven days should be sufficient to recover all your messages that you've chosen to be removed with this feature.
How the Disappearing Messages Feature Changes in WhatsApp
As reported by WABetaInfo, WhatsApp is working on a feature to let you set a 24-hour timer for disappearing messages. This means you'll be able to get your messages to disappear within 24 hours and not 7 days.
While it's not confirmed yet, this should likely come as a selectable option and you'll still be able to select the seven days time-frame if you want.
How to Enable Disappearing Messages in WhatsApp
Turning disappearing messages on in WhatsApp is fairly easy, and all you need to do is select the contact you want to send these disappearing messages to.
To do this, open WhatsApp on your phone, tap the contact you want to use this feature with, tap their name at the top, select Disappearing messages, and choose On.
WhatsApp will likely use this screen to let you choose between 7 days and 24 hours timer for your disappearing messages.
WhatsApp's New Archive Feature
It has also been reported that WhatsApp is working on an improved version of its Archive feature. In this new version, your archived chats will become unarchived when you get a new message in them.
This means, if someone sends you a message and you have their messages in your archives, WhatsApp will unarchive all those messages upon receiving the new message.
This will likely be an optional feature, as a toggle to turn this option on and off has also been seen in the reports.
Make Your WhatsApp Messages Disappear Quicker
Once these updates go into effect, you'll be able to get rid of disappearing messages sooner rather than later. You'll also get the ability to automatically unarchive your chats when you receive a new message.
Until that day comes, enjoy many of the features that WhatsApp already has built into it.