It was easy to do this in Fusetalk, but it looks as if you can't do this in VB (like you, I've gone through all the menus and options in user CP).
You have to remember that the forum menu on the left is static and would not change even if you were able to disable viewing certain forums. The only thing that could change would be the main forum page and the 'Forum Jump' drop down list in the bottom right of the webpages.