Some of properties in the Editor cannot be removed once added, also multiple of the same can be added.
Here's the list of properties missing an "X":
1.
Biomes: Terrain Objects
2.
Terrain Objects: Provides
3.
Worlds: Terrain Objects, Available Biomes
4.
Structures: Structure Cost, Can Store, Resource Conversion Input, Resource Conversion Output
5.
Units: Unit Cost