The method you use to delete text messages from your iPhone depends on whether you want to remove individual messages from within a conversation, a single conversation in its entirety or several conversations at a time. Regardless of the method you choose, all messages you delete are irretrievable.
Video of the Day
Deleting Individual Messages
Touch and hold the message until the pop-up menu appears and then tap "More."
Tap the blank circle near any other message in the conversation to select it for deletion, if necessary, and then tap the "Delete" button. The message you originally touched is automatically selected. If you want to delete all messages in the conversation, tap "Delete All" instead.
Tap "Delete Message" to confirm the deletion. If you selected several messages, the button reads "Delete N Messages" instead, with "N" being the number of selected messages; if you tapped "Delete All," the button reads "Delete Conversation." If you delete all messages in a conversation in this manner, the conversation won't disappear -- you will be left with an empty conversation.
Deleting a Single Conversation
Tap "Messages" from inside a conversation view to return to the list of conversations.
Swipe toward the left over a conversation to expose the Delete button for that conversation.
Tap the "Delete" button to delete the conversation.
Deleting Several Conversations
Tap the "Edit" button in the conversation list.
Tap the blank circle by a conversation to select it for deletion.
Tap the "Delete" button to delete the selected conversations.