Zdziarski found that the message leaves a forensic trace of the logs which could be used to recover it in its original form. "The latest version of the app tested leaves forensic trace of all of your chats, even after you've deleted, cleared, or archived them... even if you 'Clear All Chats', he said in a post.
Zdziarski said that ,"To test, I installed the app and started a few different threads. I then archived some, cleared, some, and deleted some threads. I made a second backup after running the 'Clear All Chats' function in WhatsApp. None of these deletions or archival options made any difference in how deleted records were preserved. In all cases, the deleted SQLite records remained intact in the database.”
The issue of data privacy is even more prominent for users of iPhone. Zdziarski said during a backup, WhatsApp's chat database gets copied to users' iCloud backup (on desktop as well) from the iPhone. This then leaves a user's WhatsApp data open to law enforcement warrants.
Zdziarski suggests that the only way to completely remove all traces of chats is to remove the app entirely from the phone.