Does your car have the power antenna or the stationary antenna?
I can tell you how to remove the antenna base if you have the stationary antenna. First, you have to open your trunk and pull back the trunk liner to access the antenna base. Then you unplug the antenna wire from the antenna base. Then unbolt the long shiny bracket that braces the antenna base. Then, hold the antenna base steady with a wrench, inside the trunk, and unscrew the antenna from the base. Then use a special antenna wrench to remove the chrome nut with notches in it (the chrome nut that is just above the fender, on the outside of the car), while continuing to hold the base steady with a wrench inside the trunk. That's all there is to it.
An antenna wrench is a flat, thin wrench with little pegs that fit into the notches on the nut. PM me if you need an antenna wrench, I may have an extra one I want to get rid of. And PM me if you want to get rid of your old antenna base. I'm looking for one.