You can delete a Discussion topic at any time.
In Course Navigation, click the Discussions link. There are two ways to delete a discussion topic.
Delete Discussion Topic from Discussions Index Page
Click the Settings icon next to the discussion you want to delete. Click the Delete link.
Click the title of the discussion.
Click the Settings icon to open the drop-down menu. Click the Delete link.
Click the Delete button to delete the Discussion. You can click the Cancel button or the X in the top-right if you do not wish to delete the Discussion.