Clean up a section of a mesh of a 3D relief

[FedeGSromano (Federico Romano)]

Hello everyone, I would need help understanding how to clean up the curve obtained by sectioning a mesh of a 3D relief. I would like to remove all the elements above and away from the walls and make the curves smoother without losing resolution.
Thank you in advance.

Survey Sections.gh (8.7 MB)

[Gijs (Gijs de Zwart)]

I think you will be much faster boxing out the walls manually based on this scan.