Detach the motor unit by pressing the release button.
Grasp the lid at the feeding tube and at the connection to the motor unit and turn the lid and the cube cutter accessory clockwise until the arrow head on the bowl points to the open lock symbol on the cube cutter and the arrow head on the cube cutter points to the open lock on the lid. Now you can remove first the lid and then the cube cutter from the bowl.
If you still cannot disassemble the food processor accessory, please contact the Philips Customer Care Centre in your country.