In the following steps you will only lift the battery, do not completely remove it—it's still connected to the motherboard.

Use tweezers to gently peel the battery pull tab up enough to grab.

Use your fingers to grip the battery pull tab and lift the battery up from the phone.

If the battery is hard to remove, applying a small amount of high concentration (over 90%) isopropyl alcohol or adhesive remover under the battery may help.

If the pull tab breaks, use the flat end of a spudger or an old credit card to pry up carefully on the edges of the battery until it comes loose.

The battery can catch fire and/or explode if damaged so be extremely careful.

Never reinstall a damaged or deformed battery. Replace the battery.