This is probably a bug. After removing the procedural spawner volume, spawned foliage is no longer visible. However, at runtime some of the foliage is still there.
Steps I tried to remove the spawned foliage:
- Removed spawning volume
- Delete Saved/Intermediate folder
- Removed all foliage from the editor
foliage tool, but at least some or
all affected foliage can not be
removed from the foliage editor tool.