The center cpu board is permanently fixed to the two boards on the side of it. You can't remove the white ribbon cables.

Unplug everything else and unscrew the center cpu board and the print boards left and right of it.

If you left the drive motors in place, you will need to lift the small print boards up, as the bottom of the board has a connector that is plugged into the motor.

Finally you are left with the print boards on top of the arms. Careful with removing the blue cables, they are easy to damage and have a tight fit.

If you left the arm assembly in place, you will have to lift the boards straight up because there is a connector on the bottom side of the board that is plugged into the arms assembly.