How do I delete a comment/reply in Commons?
Go to the Commons tool.

Select the Commons tool from the Tool Menu of your site.
Select the Delete link below the comment/reply you want to delete.

Note: You must have delete permissions in order to delete your own or other posts in Commons.
Confirm Deletion.

If you are sure you want to delete the comment, select OK to confirm.
The comment/reply will be permanently delete.
Note: Deleting a comment/reply to a post will not affect the original post that was commented on.