Desoldering and soldering presents a potential for device damage. Always solder/desolder in well-ventilated environments and with care not to burn yourself.

Gently lift up the front of the motherboard, at the top of the calculator.

Desolder the positive and negative terminals on the solar panel

Use the tip of a spudger to "walk" the solar panel out of its housing, by pushing it down through the two cutouts until it slides out of the bottom.

Remove the solar panel.