You can allow students to edit and delete their own Discussion posts by changing the course settings. Settings are available in the Discussions Page or the Course Settings Page.
Note: When enabled, this setting also applies to group discussions.
Discussions Page Settings
In Course Navigation, click the Discussions link.
Open Settings Icon
Click the Settings icon to open Discussion settings.
Edit Discussion Settings
Make sure you mark the Edit and delete their own posts checkbox.
Note: Unchecking this option will restrict students from editing and deleting their own Discussion posts. This permission affects posts in new discussion topics, discussion replies, and discussions within course groups.
You can also change the Discussions permissions in the Course Settings.
In Course Navigation, click the Settings link.
View Course Details
View Course Details.
Select More Options
Click the More Options link.
Allow Students to Edit or Delete Discussion Post
Make sure you mark the Let students edit or delete their own discussion posts checkbox . Once you are done making changes, click the Update Course Details button .