You can delete conversations from your Inbox when you no longer need them.
You can also delete individual messages from a conversation instead of deleting the entire thread.
Click the Delete icon.
Note: You can only delete your copy of the conversation. You cannot delete the conversation for all recipients.
Select the OK button. All messages from that conversation will be deleted.
Note: New messages sent to you by any participant in a deleted conversation will still appear in your Inbox.