Lyophilize. The ammonium formate should evaporate as ammonia and formic acid.
You may have to repeat this a number of times. Form a shell in the flask using dry ice/isopropanol. If you get a gum that still stinks of ammonium formate, add deionized water, freeze a shell, and lyophilize until you obtain an odorless powder.
Thanks Matthew... As the extraction trials were not working i went for Lyophillization only but i got traces of ammonium formate. As you suggested to repeat it.... i will do that.