I've thought better of my question; can I delete it?
If your question has good answers, though, it's not fair to have those answers removed along with your question: other users put effort into helping you and even if you no longer want the answers, somebody else might. This is why the system prevents you from deleting answered questions most of the time.
Your question was locked because you attempted to vandalize it several times by destroying all the content. The question can be unlocked, if you want to make edits that do not invalidate the existing answers, but will not be deleted since the answers may help someone else.
Since your question has answers, if you are finding that you aren't getting the answers you want, you can try to reformulate and ask a new question. If you aren't sure, you can open a question here on Meta to try to get help from the community to make sure that your question will not only be well-received, but also get the answers that you're looking for (and that, hopefully, will also help other people who have similar questions).
While we're on the subject, I've reopened the question. It is quite clearly not "primarily opinion based" since there are canonical definitions out there.