Locate the small hole just beneath the battery.

Using the sim eject tool or a paperclip, insert it into the small hole and apply light pressure downwards, prying the battery up and out of the socket.

Avoid excessive force. The battery holder can be damaged if you are not careful while trying to remove the CMOS battery.

The CMOS battery should have popped out of the holder.

During Reassembly:

You do not need to use the SIM eject tool to insert the new CMOS battery. Simply place the new CMOS battery in the holder.

Make sure the new CMOS battery is installed with the text facing upwards, as shown in the picture. It should never be installed upside down.

Remember to dispose of the CMOS battery appropriately at a facility that accepts rechargeable batteries. Do not throw away the CMOS battery.