Make the gun safe. Remove the slide. While holding your thumb on the rear cover plate, place a suitable sized pin punch in front of the lug on the striker, and behind the plastic spacer sleeve. (stiker guide on the f. pin/striker) Push forward (toward the breechface) on the sleeve, while putting downward/outward pressure on the cover plate. (caution, the parts under the cover plate are spring loaded) When the spring pressure on the rear plate is removed (by sliding the striker guide plastic sleeve slightly forward) the plate will slide down/off of the rear of the slide.
After the rear assy plate is removed the striker assembly can pulled out of the recess.
There are some videos available on youtube, etc. Most show the plate being pried off the rear of the slide. Don't do this. Once the pressure from the striker spring is removed from the rear plate.....by pulling the plastic sleeve forward slightly....the rear plate will slide right off.