deleting many, but not all, items in a folder

Outlook Web App won't let me select and delete more than about 30 pieces of mail at a time.

I don't want to delete an entire folder, but I would like to delete 10,000 of the 10,500 emails

in one folder.  How can I delete a block of 1,000 or 10,000?

I suppose I could move several hundred to a new folder and delete the old one.

But then I'd have to reprogram all the filters.