I recently noticed that some planet-unique buildings can not be destroyed (to make room for more suitable ones, or just to move them to a better position). I wasn't sure whether this was a bug until I noticed other planet-unique buildings can be destroyed just fine!
At the very least this is an inconsistency that the UI should warn about! It's quite easy to place such a building on a suboptimal position early in the game, when most building types haven't even been unlocked, and you don't know yet where you will be able to unlock additional tiles.
This is double annoying when you start the game only with planet-unique buildings that can not be destroyed and don't have the option to build anything else. Welcome to the synthetic race: at the start of the game, the only things you can use your social construction on are the Planetary Mainframe and the Planetary Extractor. Both are not bad at the start of the game, but with rising populations, even the lowliest factory type quickly eclipses the usefulness of these buildings. If only they could be replaced. But they can't.
For all I know this problem may only relate to the Synthetic Race and some of their buildings. But it's possible there are other planet-unique buildings that also can't be destroyed.
Please: if there is a specific reason that some of these buildings cannot be destroyed, you must warn about that in the description, before it's being built. Otherwise please make the behavior consistent, one way or another.