Aragon help?

I am going for Consulate of the Sea. The year is 1519 and I have the Iberian wedding PU over Castile. Problem is they got the Burgundian inheritance (while I was their overlord) and now they have 42 cities (43 soon since they have a colony in Africa that will develop into a city soon). I need them to have 40 cities or fewer in order to do the Form Spain national decision. Is there any way to reduce their city size?