Your question is answered in the Stack Exchange FAQ:
How does deleting work? What can cause a post to be deleted, and what does that actually mean? What are the criteria for deletion?
You can typically delete your own posts at will; for exceptions, see When can’t I delete my own post? below. To delete a post, just use the
delete link below it.
I have posted a question long time back and still couldn't able to get an answer.
It was only asked 12 days ago (at the time of writing). See What should I do if no one answers my question?
To get better answers, you may need to put additional effort into your question. Edit your question to provide status and progress updates. Document your own continued efforts to answer your question. This will naturally bump your question to the homepage and get more people interested in it.
If, despite your best efforts, you feel questions aren’t getting good answers, you can help by offering a bounty on any question more than two days old.
Now you don't currently have enough reputation on this site to offer a bounty, but if you want to keep the question open for a while, I am happy to offer a bounty on your behalf. I haven't done this immediately because doing so would prevent you from deleting your question.