Pressing Delete button when one or more answers exist will show a warning box "Sorry, this question has answers and cannot be deleted; flag it for moderator attention instead.".
If deleting is not allowed for question with answer(s), why does the Delete button not automatically hide?
The questioner can use the flag button if he/she wants to get moderator attention so the delete button seems useless and might hurt server performance by wasting a round trip checking. I might be wrong. I am sorry.