Insert a separate opening pick into the right edge of the phone, near the bottom.
Slowly push the pick upwards along the seam until the first clip pops free.
Due to the tight tolerances, this may be difficult, requiring a substantial amount of force. If you are having trouble, try inserting and sliding a playing card.
Once you've released the clip, leave the opening pick in place to prevent the midframe from resealing.
Grasp the right edge of the midframe by the corners and slowly hinge the edge up.
When the left edge feels loose, stop hinging and lift the midframe upwards.
Remove the midframe.
To reinstall the midframe, align it to the case, then squeeze around the perimeter until all the clips snap back into position. When properly done, the midframe should lie flat.