Stuck with a growing pop of a species that is no longer present on the planet

Some of my continental humans living on a ocean planet have modified themselves to be better suited to the climate and then some, and became radical xenophobes and militarists due to supposed clashes with vanilla humans (strangely enough, since my vanilla humans are materialists, xenophiles and individualists, so they should have been fist-bumping the new species).

Eventually, all the vanilla humans got tired of the super-humans' nonsense and emigrated, leaving behind one growing human pop, which is stuck at 0 monthly growth, despite a ridiculous surplus of food on the planet. I assume the pop is not growing due to the lack of grown pops of the same species on the planet. Being an individualist empire, I am not able to resettle or purge the pop. Worse, that pop is counted as the last member of a planetary independence movement. What can I do about this pop?