Use the edge of a plastic opening tool to pry the earpiece speaker off the adhesive securing it to the outer case. Note that the power button cable is glued to the the case as well, and will need to be pried up.

Use a pair of tweezers to unfold the earpiece speaker from its recess in the outer case.

Be careful not to tear the cable from the earpiece speaker. They are adhered together, and the cable is very delicate.