The black growing trays are removable and connect to a water valve at the back of each shelf.
The trays must be aligned on the shelf supports and fully pushed back to lock in position.
There are 'Tray stop studs' on each shelf support The tray must be pushed beyond these studs to be locked in place.
See images below
Lift the tray slightly from the front so the lip is above the studs.
Slide forward to remove.
At the right hand end of the tray is the water pipe connector. This connects to a socket in the shelf.
Align the white down pipe on the tray with the socket on the shelf and press down.
You should hear a click and the tray should lie flat on the shelf.
Press the grey button on the socket to release the connector.
Then lift the tray out of the cabinet.
DO NOT JUST PULL ON THE TRAY. YOU WILL BREAK IT.