While you can move either front or rear sight to accomplish your goal, it is both easier and "better" to move the rear. The rear sight design will take the pounding of a hammer and punch or the force of a sight pusher much better than the relatively fragile front sight, and it is not unheard of for a front blade to be bent or even snap off if a punch slips off of the very narrow base. Besides, you will need to move the front sight in the OPPOSITE direction from the rear to get the same results...that is, the rear sight is moved in the direction the bullets need to go...in this case, to the left...but you would move the front sight to the right in order for the POI to shift to the left...confused yet?

In my experience, Sig sights are very tight in their dovetails, so if you want to try the adjustment, you will need more than just a few standard hand tools...things like a brass punch of the appropriate size, a block of soft wood or babbit, etc. to rest the slide on, or a padded viceand a good flat faced hammer. Obviously, a Sig sight pusher is even better...but a bit expensive for one or two adjustments, of course. If you can find a 'smith who knows WTF he is doing...many do not, unfortunately...I would have this done...should take him all of about 30 seconds.