I have been using Firefox for quite a sometime now and have been preferring it while browsing rather than other browsers, which could be due to different add-ons available and may be due to other different positive sides of firefox but i was struggling to find out how i can delete an individual url from list of urls from history.
Then found the quite simple solution which saved a bit of my headache from further search which is "select the url and then press shift + delete keys" thats it. That will remove the url forever from visited urls, which is recorded as history URL.