There is a stretch-release adhesive tab between the battery and the motherboard, use tweezers to pull them from the gap before you begin pulling.

Peel out the adhesive strip by steadily pulling at the tab in a flat angle.

If the adhesive strip breaks, you can grab and twist it around a tweezers tip a couple of times and continue to pull.

Follow the heating instructions and place an iOpener over the battery to soften the remaining adhesive strip.