How To Delete all yahoo emails at once

After many years, finally I can do this. It is just simple. You only need to apply "new yahoo email". Otherwise, you only can delete one page at once not whole folder.
After you switch to "New yahoo Email", you need to make sure that the view of your email is not page by page (what this version of Ymail refers to as classic). It should be changed to one of scrolling views. Then you just need to check all and delete. It is just easy and simple. However I only can manage to delete all those thousand emails today..