This question already has an answer here:
Given the recent number of users who come here to complain that their account has been suspended because they deleted too many of their own questions, could a warning message be added after the first deletion which points to the policy "Your account will be suspended if you delete too many questions"?
Or even a simple: "Are you sure you need to delete this questions? See the FAQ page to learn more"
Update: See also the post-ban results for many examples of users who were suspended.