If it's a dovetail mount you could buy a dovetail sight adjusting tool from Brownell's, Midway, etc, however they are expensive for one-time or occasional use.
I just use a brass (softer than steel so it doesn't damage the sight) punch and a small hammer to tap it in the direction you want to move it.
Have you shot it yet? The front sight may well have been put in this position to properly sight it in. If that's the case, when you move it back to the center you'll have to compensate with rear sight adjustment.
