If it is like the other fans I have taken apart, there is a very small plastic clip that fits in a groove on the shaft. You can remove it by using a very small screwdriver and spreading and prying (gently!) the clip. Be ready, they tend to fly out of there when you get them off. Try and do it somewhere where you'll be able to see it if that happens. I've spent a fair amount of time looking for one on my kitchen floor. Once you remove this clip, the fan blade slides right out.