There is a tiny(really really tiny) tab on top of the suspension arm that has a slanted edge pointing towards the front of the car, and a 90 degree edge facing the rear of the car. The tab is centered over the pivot pins that slide into the chasis.
You need to push on the 90 degree angle side towards the front of the car. At this point you need to also use the tab to 'pick' the rear pivot point out of the chasis.
I have seen some arms that don't come out that easy. However you get it to come out(small screwdriver), the arm is designed to have the rear pivot point release first, so keep working that side.
Let us know if that is a bit confusing, and need more help.