Grab both pull tabs at the same time, and slowly pull to stretch the adhesive away from the battery, toward the top of the iPhone.

Follow the same procedure as with the previous strip: don't press down on the battery, keep the strip flat and unwrinkled, and pull at a low angle.

If the adhesive strip breaks off, try to retrieve it using your fingers or blunt tweezers, and continue pulling—but do not pry under the battery.