Removing National Parks?

[Ed Barker]

So I've plonked down a national park in a nice idyllic part of my empire and then some time later after researching Advanced Flight I find my only source of aluminium is inside my national park. I've looked everywhere but can't find any info on how to remove the NP so I can access the resources inside. Is it possible or an oversight? I'm sure plenty of tyrants through the course of history would have happily ripped up environmental agreements to get to some goodies to beat down their enemies. Any thoughts?