The P3s use a composite hub (plastic like) to better grab the shaft to prevent it from spinning off in-flight due to the dynamic braking introduced with them.
You'll need to grab the motor bell (outrunner) with a strap wrench or other non-scratching device and unscrew the prop from it. Be very aware of the proper direction for removal as it may be clockwise depending on which motor it is.
Just a heads up about this type of thing... My P2V+ had a hard to remove prop during my last assignment and the plastic center hub began slipping as I turned/unscrewed the prop while holding the motor still with the motor wrench. The white prop was actually turning while the plastic silver hub was not. I had to carefully saw a slot into the top of the plastic hub and turn it with a flat-head screw driver to remove it. That had never happened to me before -- and naturally I replaced it with a new prop.