Samsung Galaxy Note 7 User Manual page 122

Delete Conversations
You can delete all the messages you've exchanged with
another person.
1. From the Home screen, tap
Verizon folder > Message+.
2. Touch and hold a conversation you want to delete
and tap Delete Conversation. Follow the prompts
to confirm the deletion.
Note: Locked messages will not be deleted unless you
select Delete locked messages before confirming the
deletion.
Applications
Apps >
112
Protect a Message from Deletion
You can lock a message so that it will not be deleted
even if you delete the other messages in the
conversation.
1. From the Home screen, tap
Verizon folder > Message+.
2. Tap a conversation to display it.
3. Touch and hold the message that you want to lock,
and then tap Lock message on the pop-up menu.
A lock icon displays on the message.
Apps >
Message+