Hi Lara, the line that you can't delete is a squished down surface, those don't behave properly for click selection but you can select it by dragging a selection window around it and then deleting it.

The red piece is a little off from doing a loft between 2 curves of different shapes - when you loft the surface you make will try to connect together at equal distance traveled along each one and since the lower one is longer it's going to kind of shift towards the spiky part of it.

You can get a better idea of this by separating out that piece and using Edit > Show pts to show the surface control points, you can then kind of see how the top and bottom are connecting together from the control points.

Ideally you would get a better surface there by doing a straight extrusion downwards and then trimming it to produce the pointy shape rather than trying to build a surface directly to the pointy shape with one surfacing operation. But I'll have to see if you will be able to get an accurate enough shape to join to the other surfaces with that way.

- Michael