Set the box facedown.

Take a boxcutter, and slide the blade slightly out.

Find the seam at the bottom of the box, and gently cut through the plastic.

Using your fingers, peel the plastic wrapping back a little.

Tear the plastic off the box.

Slowly pull the top half of the box up.

Be careful! You don't wanna end up like this guy: http://youtu.be/7lhXOgJ8ahA

Voila!

Make sure you keep the box and all its contents. If you sell the phone it'll have a slightly higher resale value. Enjoy your phone!