Questions, answers and comments you make on Ask cannot be self deleted. The only items which are deleted are when moderators determine they are against guidelines.This is a good reminder to always be careful about what you say online, because what you say on the internet, stays on the internet.
You can't delete a posted question or answer or comment you done. Only the moderators are able to do that. But know that for your recent questions and answers you can edit them if you want through 15 mins only from posting them.