Quote from terraunity on December 13, 2021, 9:08 am

All placed layers in TW generated scenes are under TerraWorld gameobject in scene, expand its children, find the layer you want to edit and press EDIT PLACEMENT button to reveal editing brush tools and other settings in inspector window.

Watch these video tutorials to get started:

 

 

 

Source: https://forum.unity.com/threads/terraworld-automatic-level-designer-for-real-world-locations.784217/page-6#post-7319698