Today a new user had posted a question that received some upvotes Given $N$ integers on a circle, how to choose them in pairs to obtain minimum sum? and I had provided an answer that didn't solve the problem.
Now the PO has deleted that question and I wonder, how that is possible because if I remember right, questions that have an answer can't be deleted.

So my question is what the rules are for deleting ones own question if it has received answers, also in respect to the people who put effort in contributing to the solution of problems by providing answers and participating in discussions.