How do I delete a message from a conversation as an observer?
You can delete individual messages within a conversation in Canvas.
In Global Navigation, click the Inbox link.
Select the conversation.
Click the Settings icon  and then select the Delete link .
Note: You can only select one message to delete at a time.
Click the OK button to delete the message.
Note: You can only delete your copy of the message. You cannot delete the message for all recipients.