Is there any option to use Google 3D Tiles without the buildings, similar to the options in Google Earth?
Photogrammetry data is typically constructed of continuous mesh, where the buildings and trees integrate with the terrain as one, so currently there isn’t a method to remove select items from those meshes. However, you do have other options depending on what you’re trying to achieve.
If you want to remove all buildings, vegetation, and other items from the entire globe so that it just represents the terrain surface, you could consider using a terrain + aerial imagery dataset, such as the Cesium World Terrain + Bing Maps Imagery available within Cesium Ion. This is one of the Quick Add options inside of Cesium for Unity.
If you want to remove buildings only in a specific region, you could consider using clipping functionality to define a region, clip out the Google Photorealistic 3D tiles content, and fill it with your new content. Note: You’ll need to fill this space with a terrain of your choice, such as Cesium World Terrain or a terrain mesh / heightmap provided by you. There is more information on clipping in Unity here https://github.com/CesiumGS/cesium-unity/pull/248