The cables you're about to remove are very fragile - do not pull directly on the wires. Instead, try to pry up the connector directly, using your fingernails or a small flathead screwdriver if necessary.
Disconnect the power button and sleep light cables from the logic board.
Remove the single black Phillips screw from the front left corner of the logic board.
Use one hand to slide a spudger underneath the logic board and the other to pull back on the black sleep light unit. Lift up the with the spudger to free the logic board from the lower case and use both hands to slide the logic board toward you.
You have successfully removed the Lower Case. To reassemble your computer, simply follow the directions in reverse order.