I assume you're referring to the engine control unit (ECU).
Slide the middle cover of the water tank housing forward from its retaining clips and remove it from the control panel.
Remove the three screws located underneath.
Lift the left cover of the water tank located in the center of the control panel and detach it (clips at the front edge, brackets at the rear edge).
Pull the cover towards the center of the vehicle from the holder located below the A-pillar.
Lift the right-hand cover of the water tank located in the center of the control panel, and detach it (the front edge has clips, the rear edge has brackets).
Pull the cover from the center of the vehicle towards the bracket located below the A-pillar.
Unscrew the fastening screws from either the right or left locking mechanism, and then detach the locking mechanisms by lifting them upwards from the water tank.