Disbanding Cities

[TinCow]

I just assimilated one of those crappy tundra cities that the AI often founds. My borders will now extend over the whole area even without the city there, so I want to get rid of it. I've reduced it to 1 pop and rushed a worker, but it won't build the worker and disappear. I know I've done this before in Civ3, but I can't remember exactly how. What am I doing wrong?

[ACooper]

Manipulate food production until you have zero growth or less and no food left in you storage box. It should then build your worker.