How can I configure SpamBayes to delete spam rather than moving it?
Sorry, but you can’t. However, Outlook has an excellent “auto-archive” facility which can be used to the same effect – simply configure auto-archive to periodically delete your Spam folder. It is recommended that you configure auto-archive to keep at least a few days of Spam around, should the SpamBayes database become corrupt and require you to perform a full re-train.