Hw can I remove unknown battery

Hello ~ It sounds like your battery was repaired with a non genuine battery. Take a look here by clicking on below…

About genuine iPhone batteries - Apple Support*

*An Unknown Part  message will appear if the battery installation is incomplete or if the battery:

• Was replaced with a nongenuine battery
• Was already used or installed in another iPhone
• Isn't functioning as expected

An additional message might appear that says "Apple has updated the device information for this iPhone." This means that Apple has updated the device information maintained for this iPhone for service needs, safety analysis, and to improve future products.

These messages don't affect your ability to use your iPhone or your battery.

Learn more about iPhone parts and service history.

~Katana-San~