How you destroy cities.

[Civfan]

Using events to destroy cities is easy I thought. Just change the terrain to grass or hills or something like that. It doesn't work because the city is there. I saw in a Punic War scenario (forget which one) that when the Romans captured Carthago, the city was put to the torch. The city disappeared by changing the land under it. I used multiply events to change the land to ocean but when the city is captured, it disappears and you are promted to the city screen but the screen is for another city. I've also had a black screen. Anyone know whats going on here. Is there a way to destroy the city without going to the city screen?