Which is the most efective and quicly way to delete, for instance: 10.000 scenes; with the classical way, its impossible, I can do this by segment of 40 scene in each time.
Not sure what the classic way is, but it depends on how the scenes are arranged. If they’re in individual files, one right after the other without any scene files amongst them that you want to keep; click on the first scene file in the binder, scroll down to the last one you want to delete and hit shift-click. Then move them to the trash, and (optionally), empty the Scrivener trash folder.
Before you do that, lock the editor window; you could be in for a long wait if you end up in Scrivenings mode with the shift-click of the 10,000th document.