I was baffled by this as well. The term "Archive" is misleading; it indicates that the thing I want to permanently remove is not being removed, but relocated for possible future retrieval. I do not want to archive my old draft email/campaign, if I did, I would choose "Archive." I welcome the return of the "Delete" function.
I agree that the term "Archive" is very confusing. Maybe "Recycle bin" would be a better and more universally understood term to use than "Archive". The use of the word Archive is counter-intuitive, since the meaning of the word Archive is definitely not "delete"--it is to save or store for later use! At the very least, if someone searches for "delete draft" or something similar in the My Emma Help box, having this explanation pop up would be helpful. Thank you.