I've been trying to find a word for this concept and not had any luck in dictionaries or on Google.
If a part of a nation or state decides to separate from the whole, it secedes. Is there a term for a nation or state booting part of itself out? For a (purely hypothetical) example, if Canada decided it no longer wished to govern British Columbia and rescinded its sovereignty claims, what would that be called?
I thought of expulsion or renunciation but those are more general terms.