Pull the keyboard release tabs toward you and lift up on the keyboard until it pops free.
If the keyboard does not come free, use a small flathead screwdriver to turn the keyboard locking screw 180 degrees in either direction and try again. The locking screw is in between the F5 and F6 keys and is a clear piece of plastic.
Flip the keyboard over, away from the screen, and rest it face-down on the trackpad area.