I have 2 species of synthetic/mechanical pops in my empire. one of them is from a friendly compatriot, one of my vassals. the other is on a conquered cluster of planets, and now makes up the largest demographic in my empire. I don't want them. however, because I allow citizenship for the first species, I apparently can't do anything about the other. please, someone, tell me there is some way I can get rid of these pops. I'm already refusing them to migrate, enforcing population controls, but I am forced to allow them citizenship and not set them as undesirables to purge them. I must be missing something. how do I get rid of these unwanted synth pops without revoking citizenship from my other synth species?