Ohhhkay.

There are two separate clauses here:

"Ceterum censeo" and "Carthago delenda est".

Ceterum cenceo -> Carthago delenda est.

No, there is no need for a comma, because it works just as it does in English:

"I think Carthage should be destroyed", not: "I think, Carthage should be destroyed".

Oddly, it doesn't work that way in Portuguese, where we must add a "that" between the two clauses. But the comma isn't necessary for Latin and wouldn't make sense for it.