Deleting all threads from Sub-Forum

[dallibose]

hello all,

I want to delete all threads from a subforum. If I delete the subforum from admincp, will all threads be deleted as well??. I didn't see any option to delete subforum threads from the Prune option. And the threads I want to delete permanently have no registered users..they have been removed.

Basically they were spammers...I was wondering if the crawlers will find out the threads even though I hide the forums and my page rank may go down... What should be the best option for me??