@arjunkumar87 - what is your point?

Anyway for anyone else interested in knowing, I found a rather forceful way of deleting history including bookmarks. In my Fennec profile dir, I deleted the places.sqlite* and autocomplete.json files. Fennec automatically recreates these files if they're missing on startup.

Replace (random-chars) with whatever your random profile dir is.

Note this will delete all your bookmarks too, so use with care.