If I feel that a particular question that I asked was irrelevant from the comments and in the mean time someone has given answers to the question, is there any way that I can delete the question apart from raising the flag for the moderator.
The general rule is, you can't. The exception to this rule is that it's possible to delete a question that has no upvoted answers and no accepted answer.
Since your post has got upvoted answers that means people other than yourself have also contributed content deemed valuable by the community and thus the delete function is disabled.
You agree that all Subscriber Content that You contribute to the Network is perpetually and irrevocably licensed to Stack Exchange under the Creative Commons Attribution Share Alike license. You grant Stack Exchange the perpetual and irrevocable right and license to use, copy, cache, publish, display, distribute, modify, create derivative works and store such Subscriber Content and to allow others to do so in any medium now known or hereinafter developed (“Content License”) in order to provide the Services, even if such Subscriber Content has been contributed and subsequently removed by You.
In general there is no such way if there is already an upvoted answer to the question. In this case only a moderator can delete the question and you would have to flag it for moderator attention, explaining your reasons for deletion.
However, note that this alone is not a guarantee for the question to get deleted. It is still up to the moderators to decide if your request is valid. You have to keep in mind that nothing you post here is owned by you and valid and valuable contributions should not be deleted without good reason. Those questions aren't asked for you alone and the fact that you consider the question irrelevant doesn't mean the community does so, too. The moment you post your question it's owned by the community and if the community sees value in it, it should not be deleted.
If you feel the question is invalid due to the site's rules is a different thing. In that case you might properly explain your reasoning in the flag, or maybe just use your natural right and abilities to close-vote (or close-flag) it without the necessity for moderator attention.
And last (and actually also least), if you are very embarrassed by an otherwise valid and valuable question and don't want your name pulbicly associated with it, you can choose the option to disassociate your account from it. But this also means the question doesn't have an original asker anymore, who could clarify the question further if necessary or accept any possible answers.