keep in mind by deleting the messages, you’ll only be deleting messages from your iDevice. First, lets start by deleting specific messages from a conversation. Launch the Messages app, in your Messages app, tap the chat containing the message you want to delete.
In the conversation, tap and hold the message you want to delete.
When the pop-up appears, tap “More…”.
Tapping “More” reveals empty radio buttons to select one or more messages in the conversation. Select the messages that you want to delete, then tap the trash can icon at the bottom left.
Note: make sure to select the proper message IOS will not ask you to confirm the deletion.
Delete an Entire Conversation
Just slide a conversation to the left to reveal a Delete button. Tap the button to delete the entire conversation.
Delete Multiple Conversations at Once
On the Messages screen, tap “Edit.”
Tapping “Edit” reveals empty radio buttons on the left to select as many chat conversations as you want. When you’ve selected the conversations you want to delete, tap “Delete” at the bottom right.
A simple, straightforward process.