Its easy..
Pull DOWN on the triggerguard and offset it. Pull back on the slide all the way, and lift the back of the slide upwards, then the slide should slide forward off the frame. BE VERY CAREFUL.. the bolt hold-open device operates on a TINY spring that is easily LOST if you don't take this part off carefully.
That's about as far down as I'd take it for general cleaning and maintenance.
Dr.Rob