User blog comment:ThomasSirHandel/User blog:How do you delete all the pages and photos on a wiki at once/@comment-1330470-20130611171140

Questions like this are best for the forums. I might as well say, though. There is no end-user tool for mass deletion of pages, only the regular delete page.

VSTF and Staff have a tool called Special:Nuke available to them, which I have never seen nor used but I suppose it is for mass deletion of pages.

It sounds like you basically want to start your wiki over. In this case, you might go to Special:Contact and ask your wiki be deleted, and ask that the URL be made available so you can re-create it at the same location, brand new.