You should be able to remove the long screw then push the physical sensor out of the double pronged aluminum bracket. As lpaulabbott said, you will also need to rotate the balancer so that the window is centered so that the sensor itself is clear of the reluctor ring. Also, make a note which slot the reluctor ring passes through so you don't re-install the new one and use the wrong slot. Been there done that. The sensor is made to come off the bracket, this is why some parts stores sell just the sensor without the bracket.
HTH.
Patrick