You have to take a punch and hammer and remove the pin at the bottom rear of the grips. You can see the pin in your picture. This pin also retains the mainspring or hammer spring so be aware of that. Once you have removed the pin, lift the grip panel up at the rear and pull towards the rear. There is a notch that retains each grip panel on the front edge. It is not difficult, I replaced the grips on my Model 915 about a year ago.
