I want to permanently remove a WhatsApp conversation so it cannot be recovered later. I understand that older WhatsApp backups may contain deleted chats. If I delete the conversation from my phone and computer, then create a new backup right afterward, would that remove it from the backup permanently? What other copies might still exist, such as on the other participant's device, linked devices, or older backups?
2 Answers
Deleting a chat only removes it from your own WhatsApp view. It does not delete the messages from the other person’s phone. The “Delete for everyone” option is separate, has eligibility and time limits, and may still leave quoted messages, media, or notifications behind.
A new backup generally reflects the current state of your WhatsApp data, so the deleted chat may no longer be included in that particular backup. However, this does not guarantee permanent erasure. Older cloud or local backups, phone backups, linked devices, exported files, notifications, media, and the other participant’s device could still contain copies.

So both people would need to remove the conversation and any related backups or files on their own devices. Even then, you cannot control copies that were exported, screenshotted, backed up elsewhere, or stored by the other person.