Step 1:
 - Create Telegram Clinet app id by using https://my.telegram.org/auth and create a client app and copy API_ID, API_HASH

Step 2:
 - download tel_v1.exe from https://mrrsoftsolutions.com/
 - Unzip and Run the solution, it will list all your subscribed channels and groups, even user chats as well 

Step 3:
 - edit the listed channels u want to delete 
   (Make sure the list will contain only the channel thats you want to delete perminently, 
    please REMOVE the channel from the list if you wish to "Do Not Delete")
 - click Delete button for final execution.


