How to delete all Mails at once?

Hi, what must I do, to delete all mails in complete in IOS 11.3? Generally it is told, thast I must mark them one after the other and than push the delete button. This is very elaborate, there are more than 3000 Mails to delete.

Hallo, wie kann ich sämtliche Mails im Posteingang auf einen Schlag löschen?