I was sleepy eyed when reading a text and a statement did not register in my mind. Asked it on MSE, and promptly downvoted,but got a detailed answer. It was later put on hold for lacking context. I do not know what context can be added. Also, as my doubt was clarified anyway should I just delete the question? It seems rude to me to slight those who answered me kindly. Advice? (am a novice at SE).
Since nobody else has answered... You can't delete the question because it has upvoted answers. That's precisely for the reason you identified: it would negate the effort put in by those answerers. So no, don't delete it. If you're worried about the question accumulating more downvotes, the best thing to do is edit it to improve it. Add in some statements of what you tried and why they didn't work. If you really can't come up with anything to add in, you're probably best off leaving it alone, and remembering that you shouldn't ask such questions next time. (I might suggest not posting questions when you're too tired.)
If the question didn't have upvoted answers, then it's probably okay to delete it, but I would still do so with some caution. If there are zero-score answers that seem like they're good, you might want to avoid deleting the question, because perhaps the answer will be helpful to someone, and the only reason it wasn't upvoted was a lack of attention. On the other hand, if all answers are downvoted, then you can safely conclude they probably aren't helping anyone and delete the question. Keep in mind, however, that deleted questions do count toward a "question ban" - a temporary (I think) block on posting new questions. If you delete one question, it's not something you have to worry about, and if you post many more good questions than bad ones, it's not something you have to worry about, but if many of your questions are downvoted and/or deleted, you might find yourself unable to ask more. Deleting does not help you in this case.