How to permanently delete contents of a foder?

Hi

I have a mailbox, having a folder (let us say TOPFOLDER) contains bulk emails. I want to delete them all at once. If i delete them through outlook or OWA, it will take forever. Is there a shell way to delete the content of this specific folder keeping the folder as is?

Is there a rule that i can create in the server to delete whatever emails in this folder should be deleted in every ten days, for example?

Thanks for your support.