https://www.entrepreneur.com/article/370824

Do you want the messages of a conversation on WhatsApp to self-destruct? The instant messaging application already has a feature for this called “temporary messages”.

Once you activate this option, new messages in a chat will disappear in a period of seven days. Beware: this feature does not affect texts sent before you activate it and your contact will have ways to save them, likewise, multimedia files will not disappear from anywhere outside of the chat or from the devices where they have been saved.