I know this question has been asked before but how do you delete a question that you have asked?

Under Yahoo's current setup, you can only delete your question if it doesn't have any answers. Once a question gets its first answer the option to delete is removed from the edit button so then the only way it can be deleted is if it's reported as a violation by other users. That said, what you can do is use the "make anonymous" feature found in your edit button to remove your username and avatar from it, this is most helpful if you have a question that's embarrassing. Also, if on mobile make sure you switch over to the desktop mode.

1) The question must have ZERO answers

2) You must be in DESKTOP mode.

Only if both those are true will there be an option to delete on the EDIT link/button.

you can't