Simply remove the rear sight and remove the ejector plunger spring then reassemble. There is no reason to remove the plunger. DO NOT consider removing "Part 10" as one idiot suggested, that is the ejector and the gun won't function without it.
The magazine dis-connector functions by simply pushing down on the drawbar so it won't engage the hammer hooks or sear.
This feature is identical on all generation S&W Automatics. The principal change in the slides was the way the rear sight was mounted. The years I was a PD Armorer we would dis-able the magazine safety for any officer that requested it.