The screw can be removed, but it's VERY delicate work. You would need a drill press, a 2mm left-hand drill bit, and a very gentle touch.

Drilling down in reverse (counter-clockwise) into the exact center of the screw from a perfectly vertical position (that is, in line with the screw hole) at a slow speed will cause the screw to back out of the hole. That's the same basic procedure as removing any broken screw.

To minimize the chances of slipping, it would need to be done with a drill press, not a hand drill. The motherboard would be attached to a piece of plywood using standoffs, and the plywood would be secured to the table. It's important that it not move at all while the screw is being drilled.

The screw itself is 3mm in diameter. Using a 2mm bit reduces the chances of thread damage to the standoff.

Obviously, if you slip at all you will most-likely destroy the motherboard; so I'm not actually suggesting that you do it. I'm just telling you how it can be done if you want to take the chance.