To know if someone has deleted their Telegram account, you cannot directly confirm it yourself because Telegram does not notify other users about account deletions. However, there are indirect indicators that might suggest an account has been deleted:

  1. Inability to find the user in Telegram's search or by entering their phone number.
  2. If you previously had a chat with the user, the conversation might disappear from your chat list, or you'll see a message indicating that the user has left Telegram.
  3. If the user had a public account or channel, it would disappear from the platform.

To delete a Telegram account, a user can follow these steps:

  1. Open a web browser and go to the Telegram Delete Account or Manage Apps page (https://my.telegram.org/auth).
  2. Enter the phone number used to create the Telegram account.
  3. Receive a confirmation code sent to devices logged into Telegram.
  4. Enter the code and click "Sign In."
  5. Explain why the account is being deactivated in the "Why are you leaving?" section.
  6. Click "Delete My Account."
  7. Confirm when asked, "Yes, Delete My Account."

After completing these steps, all messages, media, contacts, and data stored in the Telegram cloud for that account are removed. It's worth noting that Telegram accounts can also be deleted automatically after a period of inactivity, which can be set in the Telegram app's settings.

Please note that the account deletion process is irreversible and all data associated with the account is lost.