Slowly pull the adhesive tab away from the battery, toward the bottom of the iPhone.
Pull steadily, maintaining constant tension on the strip until it slips out from between the battery and the rear case. For best results, pull the strip at a 60º angle or less.
If the strip breaks, carefully try to retrieve it with your tweezers (without damaging the battery) and continue pulling. If the strip breaks off underneath the battery and can't be retrieved, continue with the steps below.