Remove the plastic washer
Peel back the right hand adhesive tab. Pull it down and resist the need to pull it against the battery. This can rip the adhesive tab.
Keep pulling the tab. You will feel it slide out from under the battery. Once it is fully out you will feel increased resistance. Once the increased resistance is felt move on to the next step.
Sometimes the adhesive tab can rip. If this happens try to catch the end and pull it out.
If you can’t get the tab then you can heat the case of the phone gently with a hairdryer. This will melt the adhesive and help you remove the battery.