There are 6 clips holding the top cover to the base.

Press in at the red arrow, by the water reservoir retention hook, to detach an internal retention clip.

The clips are outlined in red in the second image.

Pry up on the top cover at the orange arrow to begin unclipping the top of the unit.

Two additional clips are at the yellow arrow on either side of the unit. Pressing in at these locations aids in their removal.