the damage is not deep (its on surface only), i do not see the threads. It's front wheel on driver's side. Holds pressure, though I am wondering if the replacement is needed. thanks!
It is not easy to answer such a question directly because this particular damage would need a slight further investigation. If the "sliced" piece is lifted a bit can you confirm that the rubber underneath is in good shape without any more foreign objects pinned on it? Can you measure the rubber thickness underneath the sliced piece area and confirm it to be close to the minimum tire thickness indicated by your tire or alternatively by rising the sliced piece can you see the slice going deeper than the grooves depth? FYI the minimum tire thickness is usually indicated by a small bump indicator higher (thicker) than the grooves themselves.
Also if you drive your car near your usual maximum speeds do you feel any bumps or vibrations (caused by the piece protruding out while centrifuged)?
You could always visit a tire specialist and A) ask for a preventively internal patch just to avoid leaving this area thinned out or B) ask for a replacement used tire.
Finally, since from your provided picture it is obvious that your overall tire condition is not mint, you should consider changing you tires some time soon so you could avoid dealing with it immediately. Anyway you should be cautious over it because it is your life (loved ones too) riding on this tire.