how did that stem fit? i got one for my bike, bargain off CRC, just wouldn't fit over the steerer on my pikes... Well, it did, it just took bloody hours and a load of WD40 to get it off again!
The stem stays clamped by the wedge system. You have 3 bolt holes on the wedge. The middle one is for extraction, the other two are for keeping it secure.
To remove the stem - remove BOTH screws completely, then screw one into the MIDDLE hole. It pushes the wedge vertically upwards (i.e out..) and you can remove the stem by hand. Magic :-)