These would be isocurves. You can turn them off in the display settings of Rhino by setting them to zero width:
Tools/Options/View/Display Modes/Shaded/Objects/Surfaces/Isocurve Width
These would be isocurves. You can turn them off in the display settings of Rhino by setting them to zero width:
Tools/Options/View/Display Modes/Shaded/Objects/Surfaces/Isocurve Width