I need to replace the steering sector in my 4X4.

Not sure what part you're referring to but it's apparent you don't have the rack and pinion steering system. There's three ways to separate a tapered stud for steering linkages. One is to use a pressing tool that you'll likely find at an auto parts store that rents or borrows tools. The second is to bang on the link alongside the stud to shock it free. If the part with the ball and socket is going to be replaced, you can use a pickle fork. Those wedge between the two parts to force them apart. Some you pound in with a hammer and some are used with an air hammer. Those usually wreck the dust boot and they put a lot of stress on the ball and socket so pickle forks aren't a good choice for parts you're going to reuse.