There is no need to delete it
Sure, you lost some rep as the question is now at +1/-5, which totals -5 reputation. But other than that this is not really a problem. If you really want to you can delete the question, but in general the community prefers to keep questions if there is an upvoted answer. Otherwise it would automatically get deleted after some time. Currently the only answer is at +0/-0, so your question might still fall into that category and the system might decide to delete your question in the near future.
The general process however would be to just keep it around. If there are upvoted answers it means that someone spent some time to help you and the community approved of his efforts. Taking that away is something that in general is not a good thing and the community doesn't like to see such a behaviour.
Edit the question
Your question has been put on hold pretty recently. An edit from your side will automatically send it to the special reopen review queue. This is the preferred process so that people can judge whether the question is now on-topic or not. Especially with a question that was put on hold recently this should be the first thing to do.
If you feel that it won't make any difference, for example because there is a very highly negative vote count and you suspect people won't look at the question again, as questions with a total of -4 disappear from the active tab on the main site, you can try other things.
Ask a new question
You can just ask a new question. If you feel people will jump and say "but that is the same thing you already posted yesterday!" because you copy-pasted a lot you should make sure to state how your new question differs from the old one.
Use the Sandbox
We have a Sandbox on Meta that is designed to help people who have problems with making a question on-topic. A lot of people use it, even if their reputation count would sometimes suggest that they would know how to ask questions. Asking questions on WorldBuilding can be extremely difficult at times, which is why the Sandbox was created. It happens to everyone sometimes that their questions get closed. Don't worry about it.
The answer is currently at +0/-0, so the community didn't think too highly of the answer. Your question is at +1/-5, so the community didn't really like your question and sent it away from the active tab. That makes recovery pretty hard.
I'd say you should decide how much you appreciate the effort the author of the answer put into it and decide whether you want to upvote it or not. If you want to upvote it please go ahead and do so - and consequently don't delete the question.
In the other case you can just leave the question and wait or directly delete, depending on what you feel would be best to start a new question. With a deleted question it's easier to start a new one, as it can't be marked a duplicate.
In any case you could give the Sandbox a try and see how much feedback you get. We encourage people to wait at least 24 hours in the Sandbox for feedback before posting the question on the main site. If you delete the question or wait for it to get deleted you might want to copy some of the comments if they could be useful so that people in the Sandbox with less than 10k reputation can take the comments into account when giving feedback.
What to do better
Well, to be honest: your latest edit was pretty good. I know that it looks like pedantry at first, but just saying "What's the best?" is really opinion-based, because we don't know what you focus on. The best for flying in the open? The best to hide on a stealth mission? The best regarding effort of flying?
Michael is right that "What's the best?" is not a good question, but I personally think that "Which one is better for flying?" is perfectly on-topic and that it looks like any other creature-design question I've seen on the site.
I don't know specifics about this topic, apart from the occasional question that always seems to mention "Everything above 70kg won't fly on our current Earth", but it looks like answers could easily say "It won't fly on our Earth, but ignoring that - first one has the following advantages/diadvantages over the second one". Maybe you could add something to make this clear?
Anyway, I voted to reopen and gave you and upvote. If you choose to rework your question and post a new one you will probably have me on your side.
Part of that might be that I love creature-design questions and haven't looked at yours until now.
Some questions you might find interesting
These questions were mainly found by searching: winged is:q
What is the maximum size of a flying creature?
Air density for winged human flight?
The Four-Winged Angel
What should dwellings look like for a winged humanoid?