Final answer:
France is the colonial power that still retains control over its colonies in the South Pacific, such as French Polynesia, despite other colonial powers having relinquished their territories.
Step-by-step explanation:
The country that has not relinquished any of its colonies in the South Pacific is France. France colonized a large number of islands in the South Pacific during the age of colonial expansion and retains control over them even today, with French Polynesia being among the most significant. While other colonial powers have released their claims on various territories around the world, France has maintained its colonies as external departments or territories, with French Guiana being another example of a region that has remained under French control.