Telegram Now Lets You Delete a Received Message From Sender's Device March 24, 2019 https://www.bleepingcomputer.com/ne...elete-a-received-message-from-senders-device/
Yeah, or make screenshots, photograph the screen, use a modified client that does not delete messages etc etc.
Telegram fixes bug that failed to delete ‘unsent’ photos and videos September 9, 2019 https://techcrunch.com/2019/09/09/telegram-bug-delete-unsent-photos/