You need to drill out the "rivets." They are actually snap-off screws. When they are tightened, the head snaps off so that it cannot be removed to enable thieves to steal the car. If you replace the key lock cylinder, you need new keys. This means you will have 2 keys. One to turn the car on, and another to open the door/trunk.
And please stop typing in all caps. You have no idea how difficult it is to read when the system changes you all caps to first-letter only caps.
I suggest playing with the key-lock cyl some before you replace it. I thought I needed to replace mine, because it had the same issue. Turned out the guy before me had pulled the key out when it was in the Accessory position, and each time I put the key in it didnt insert fully, preventing me from moving it to the off position.