Looking at the code for modules/News.php for version 0.2 I see that there is no way to remove news short of manually removing them from the database yourself.
However the version of modules/News.php in the trunk has got support for !news rem <id>. Also it makes a [delete] button accessible for the poster and any admins.
Note that the version of modules/News.php in the trunk uses the new security module so if you haven't got that working the module in the trunk isn't a drop-in replacement.
- BlueEagle