I want to permanently remove a WhatsApp conversation and make it as difficult as possible to recover. If I delete the chat from my phone and computer, then create a new backup immediately afterward, would the older backup be replaced so the conversation is gone? Could it still exist on the other participant's device, in their backups, or somewhere else?
3 Answers
WhatsApp generally says it does not keep a readable permanent copy of delivered messages on its servers, but that is different from deleting copies stored on phones, computers, or cloud backups. The safest practical steps are to delete the chat and media on your devices, remove old WhatsApp backups from the relevant cloud or local storage, and ask the other participant to do the same. That still cannot guarantee recovery is impossible.
If you need a message removed from the recipient’s phone, deleting the chat is not enough. WhatsApp’s “Delete for everyone” feature is the relevant option, and it has a limited time window and other restrictions. Messages may also remain in notifications, screenshots, exports, linked-device storage, or backups, so there is no universal way to guarantee that every copy is destroyed.
Creating a new backup after deleting the chat should prevent that conversation from being included in the new backup, but it does not erase every existing copy. Older cloud or local backups may still exist until they are replaced or deleted, and WhatsApp backups can be separate on different devices. Also, deleting a chat only removes your copy; the other person may still have the messages and their own backups.

So both people would need to delete their copies and remove or replace any older backups for the conversation to be absent from those backups. Even then, that does not guarantee that no other copy exists.