To delete a contact on iOS, open the Telegram app and tap Contacts in the bottom-left corner. Then, long-press the contact you want to delete and tap Delete Contact in the menu that appears.

This post shows how to delete a single or all of your Telegram messages and history locally and in the cloud - Received or Sent!

Follow this step-by-step guide to delete your Telegram account and associated data from Telegram’s servers to protect your privacy.

I especially love Telegram’s new approach for auto-deleting old messages: The app can now auto-delete entire conversations for both parties.