I would use a plugin rather than a template hack, and set the variable $show['reportlink'] to false if the forumid matches the desired where it should be turned off.
I have a product, whose latest version you can get here:
https://mathhelpboards.com/vbulletin...use-22022.html
The primary goal of this product is to discourage report abuse, but it can be configured to simply do what you want.