You must be logged in and have System Operator privileges to delete comments.
To delete any comment posed you have to edit the Discuss page manually. You can go to the particular Discuss page after logging in and doing one of the following:
1. Click Special Pages > Click All Pages > Select Discuss namespace > Search for the page title.
2. Click Recent Changes > Click ‘Discuss’ link beside any Article link
3. You can also go to any Discuss page by doing the following.
If a there is an article titled Test and the link is
just add Discuss:before the article name and browse the following: