To manually stop students from posting replies to discussion posts, you can use the Close for Comments option.
- You can automatically set your post to close for comments on a specific date by creating discussion availability dates.
- For graded discussions, the Close for Comments option will not appear until after the discussion due date.
Close from Discussions Page
To close a discussion from the index page, locate the discussion. Click the Options icon  and click the Close for Comments link .
Close from Individual Discussion
To close comments within an individual discussion, click the title of the discussion.