I created a curved line but I cannot intersect it with a face so I can delete the upper half was looking for a way to either delete the overlapping line with an object or explode the line and select only the visible parts is there any way?
Share the .skp file so we can see what you’ve got.
You should be able to draw a line (in the same context as your curve) where you see the red x Intersection inference. That will break the curve at the junction, and you can delete whichever part you don’t want.