It took me two hours to work this out and only then after finding an exploded drawing of the door on the Neff website.
There are no screws to remove. Just open the door flat and grab the edge of the glass panel nearest the oven. Apply gentle pressure towards you and upwards and the panel should slip out. Once removed you can clean all three glass panels.
This also give you access to the two screws that secure the handle and which hold the top end of the door together.
Robert, January 2011