To delete a WhatsApp group chat completely , follow these steps  :

1. Open the WhatsApp app on your phone.
2. Go to the group chat you want to delete .
3. Tap on the group name at the top to open the group info . 
4. Scroll down and tap on “ Exit Group ”.
5. After exiting the group ,go back to the group info page .
6. Scroll down again and tap on “ Delete Group ”. 
7. Confirm the deletion when prompted .