As @tech_ni says the battery is dangerous! Lithium batteries do not stop burning and ignites with the smallest puncture! Remember the Note7? Use a nylon spudger and a decent amount of >99% isopropyl alcohol. The iso makes the adhesive a lot weaker, and with carefully using the spudger as sort of a breaker bar, you can carefully pry out the battery.
Dispose of the battery safely, according to your local recycling laws. Lithium can be VERY dangerous!