Remove cotter pin, get a socket 1/2 inch drive and remove outer nut that should be the thick one wedge prop with block of wood, then loosen but do not fully remove inner bolt. Buy, rent or borrow a prop puller, may have to heat hub, nut keeps prop from flying off. Then remove nut and prop. Maine Sail has a great tutorial on his blog on lap fitting the prop to the shaft correctly. Also make sure key is fit correctly. To refit, you can use thick nut to run prop home but then remove it and replace with thin nut against prop hub, outer nut should be the thick nut, use a torque wrench, and finish with cotter pin. Lots of good videos on YouTube but Maine Sail blog details it much better than my ramblings. If you plan to have the prop inspected by a prop repair shop they will lend you the prop puller.