When you pull out the battery, its left edge will come up, but the right edge will not. You'll remove the remaining film and the battery in the next step.

Firmly hold the phone in place and grip the blue center pull tab.

Pull straight up to separate the battery adhesive using firm, steady force.

If you're having trouble, apply 1-2 drops of high-concentration (more than 90%) isopropyl alcohol to the left edge of the battery. Lift the left edge of your phone and wait one minute for the alcohol to soften the adhesive.

Lift the battery until it is perpendicular to the phone and hold/rest it in the right edge of the frame.