lolol
why don't you try to send out mass emails of "hey, remember us? yeah, we're still here and yes there is a forum on RG..." instead of just deleting.
Also, if you want more use of the BBS, mention it in front page newsposts, or if somebody is having a contest, say you gotta post in the BBS that night to win.
That's the main reason it gets use when you delete it, it's because you make a news post saying "oops, deleted it again" and then people are like "woah, I forgot about the forums" or "woah, this places has a bbs?!" and they click the "forums" link, and find it.
btw, delete the NGBBS instead