You can believe in a greater order that governs all things, and that you should burn the cities to uphold that order. There just has to be a straight reason behind it.

You can be an OG conjurer who is about keeping planar whatever in due shape because otherwise the world ends. Killing an abomination or two in the city because of it? No problems.

But that being said, if you're going to break laws under an orderly character, make sure to back it up with role entries or RP that explains it, because by default that's not really expected.