The "News forum" can't be deleted from "weekly format" courses, though it can be deleted from "topic format" courses.
I noticed this problem last year when using Moodle 1.6.4. To solve the problem, I just had the teachers "hide" the "news forum."
I wonder if you would consider this a bug, or is this the expected behaviour.
This problem still exists in Moodle 1.8+ (April 11, 2007 Version)
What happens is this.
1. A teacher deletes the "news forum." (In "weekly format")
2. It seems to go away.
3. But the next time the course is accessed, it has "magically" reappeared.
For courses in "topic format," this does not happen.