How do you convert a colony to a core?

[Shau]

Playing in south madagascar. For some reason betroka became a colony and wasn't integrated. Meaning control max is 9% at the moment. How can I fix that? I was able to conquer Manabondro. Beside that, I only colonized my starting province and they all became cores. I was able to convert Manabondro to a core too. But I cannot find a way to convert the colony.

https://i.postimg.cc/VsFY0mhp/image.png

[TENTARA]

to convert it to a core use advisor action, from converting religion/culture etc. , i played UK and successfuly coring some of Mali reguin by doing that, it really take a long time oc