The RAM chips are being held in place on either side by small spring-like levers.

Simultaneously pull both of the levers out by the tabs shown circled in picture one, and the RAM chip should lift itself, awaiting removal.

Simply pull the RAM chip out of its port, and it is ready to be replaced with a new RAM chip.

Note that each bay has a line roughly 2/3 of the way to one side, and that determines which side of the RAM module goes up when replacing it. (Shown circled in picture 2)

Also note that the levers should click back into place, locking the RAM in when it is pushed down all the way, but the RAM should not click into the port. The RAM chip slides into the port, then pushes down and clicks into place.