See how to remove and install grips on a Luger P08 pistol (also known as Pistol Parabellum). You'll need a good gun screwdriver set, and you'll be ready to take that grip off of your weapon.
Be sure to follow all disassembly and assembly instruction found in the technical section of http://www.lugerforum.com.
If you are not sure of what you are doing or if the gun is not working properly, take it to a competent gunsmith.
Be sure to follow all NRA firearms safety recommendations.