How to clear the text message inbox on iPhone 6 plus?

Currently, you can only delete the information of one contact at a time in text messages (swipe from left to right or from right to left to select delete), and all text messages cannot be deleted. If you need to delete all conversations in a contact, enter the contact, select "Edit" and then "Clear All". To delete only a certain conversation, select "Edit", click on the conversation you want to delete, and select "Delete".