If it is purely to remove the drawer for cleaning then pull as far as it will go. Feel underneath, slightly left of centre where the sloping meets the flat bottom. The ridge has a little notch in it that will lift if you press upwards on the ridge and pull out gently at the same time. Push up harder and tug harder a little at a time until it eventually gives way. Replacing is simply a case of pushing back in.
Good luck.
IAN
December 2005