Trying to delete a line without messing the face

SketchUp
1

Hello. I have been working on a project where i had to plot land on landscape. I had originally finished but now have to make changes to the land layout. I deleted the plot but im having problems deleting a line without it deleting the face.

line
line714×570 116 KB

The line in the red circle is what im trying to delete. Any ideas? Attaching the sketchup file as well. Many thanks
land.skp (8.5 MB)

2

You just need to soften it, here I have use ctrl with the eraser tool.
Edge

3

Been trying to figure this out for hours. Thank you so much!