To delete your Telegram account, you'll need to go to the deactivation page on the Telegram website. From there, you can enter your phone number and confirm that you want to delete your account. It's a simple, no-fuss process that only takes a minute or two.
One thing to keep in mind is that deleting your Telegram account will also delete all of your messages and contacts. So, if you're looking to preserve any of that info, you'll want to export it before deleting your account. This is a good opportunity to start fresh and get rid of any clutter, though!
