Is it permissible to kill one's paternal uncle in order to inherit from him, or what is the legitimate way to inherit from one's paternal uncle?

If your uncle seizes the inheritance and prevents the heirs from receiving it, he is an oppressor and an aggressor. The correct way to reclaim your right is to resort to the court. Killing him is not permissible; rather, it is a greater injustice and aggression than his injustice, because unlawful killing is one of the gravest sins. Allah has threatened whoever intentionally kills a believer with Hell, His wrath, His curse, and a tremendous torment. Furthermore, a believer remains within the latitude of his religion as long as he does not shed unlawful blood.