Figuring out how to remove unnecessary line when export to google earth


I have followed the tutorial to create a park, when I export it to google earth.
There are some extra lines shown in the model, that I don’t know what they are.

Landscape exercise.skp (15.4 MB)

I guess those are contour line perhaps ( in yellow and red colour)

Also attached with the exported file in kmz format
Landscape exercise.kmz (5.5 MB)

It could be due to incorrect tag usage in the SketchUp model. Those contours, among other geometry show up when the tag usage is fixed. All edges and faces should be untagged.
Screenshot - 5_17_2022 , 11_30_06 AM

The contours should also be grouped.

You should also make sure faces are correctly oriented. There should be no exposed blue back faces.