Open a web browser and go to https://my.telegram.org/auth
Enter your Telegram phone number in international format
Enter the confirmation code sent to your Telegram app
Sign in to the Telegram account management page
Select Delete account
If prompted, enter a reason for leaving
Confirm the deletion
Note that account deletion is permanent and cannot be undone
If you want to delete the account from the Telegram app, use the app to access the deletion link in settings or use the official deactivation page in a browser