I am aware of the own question deletion rules - in particular, kindly provided in an answer to Rules for deleting one's own question by Martin Sleziak. I think these rules have to be changed somehow. Maybe add a rule that, once there is an answer, the question cannot be deleted during, say, 24 hours.
Here it is again: the question derived tensor product and finite projective dimension has been closed by the OP in about half an hour after receiving an answer. There was presumably not enough time for the answer to get any upvotes (whereafter the OP would not be able to delete it anymore).
Although I voted for undeletion I am not tagging this as an undelete request since I am not completely sure whether it must be undeleted or not. What I am sure about is that there was not enough time for the community to see the answer and decide.
PS Contemplating the answer by Todd Trimble, another possibility came to my mind: why not leave the prerogative of closing a newly answered question to moderators, and, if OP tries to do it, respond with an instruction to approach moderators for that?