Please, next time send me the file, before deleting it!
Only in this way we can understand where is the trouble...
The contour lines are a simple Library Part, if you want to delete it you can simply select it (the hotspots are on its bounding box, or you can find & select the object by its name) and then delete it.
If you want to restart from the original model:
1. select the mesh and delete it
2. select the roads and delete them (in the latest update you can avoid to delete them: select them and disable parameter "the road is processed" in the object settings dialog box. In this way you will preserve all your roads settings, also the section levels changes)
3. delete all the plateaux
Now you have in your ArchiCAD Plan only the points/hotspots and the outiline/fill.
Select the outline/fill and calculate the terrain once again.
If you need further info, please don't hesitate to contact me.
Friendly
Fabrizio
Fabrizio Diodati
Graphisoft Italy Srl | Via Rossignago 2/A Spinea Venezia 30038 Italy