How do i delete the forum database ?

[OO-HELIOS]

I hope this isnt a too stupid question.
I want to delete everything in my forums(Threads,posts,members,signatures...) The only thing i want to keep as it is,is the forum names and sections.How is this accomplished?
I wouldnt want to delete every single thread ,every single user manualy...
Please help !

[Jake Bunce]

Admin CP -> Threads & Posts -> Prune

Admin CP -> Users -> Prune / Move Users