AssetBundleUnloadOperation Asynchronous unload request for an AssetBundle.
Unloads assets in the bundle.
When unloadAllLoadedObjects is false, tracking data structures and any memory buffers holding content of the AssetBundle will be freed. But any instances of objects loaded from this bundle will remain intact.
When unloadAllLoadedObjects is true, all objects that were loaded from this bundle will be destroyed as well. If there are GameObjects in your Scene referencing those assets, the references to them will become missing.
After calling UnloadAsync on an AssetBundle, you cannot load any more objects from that bundle and other operations on the bundle will throw InvalidOperationException.
Additional resources: UnloadAllAssetBundles, Unload, Using AssetBundles Natively.