A fast way to hide an object is to right click on the object to open a contextual menu and choose Hide in the contextual menu.
Learning to use these contextual menu is a must with SketchUp (SU) and any other program that support them to get proficient.
Click in sequence on the scenes tabs of this SU file for ideas. You can hide the edges (bottommost edge for the second floor and topmost edge of the first floor as described in previous post to get a better looking outside walls.
Sorry Gully missed that.
I usually look for title. I have the old 2011 tut you did and was looking for that. Wish there was better data base capture approach.
Side-click on the offending line. In the popup menu, there will be a choice called “soften”. The line will still be there as the edge of whatever it is the edge of, but the space on either side of the line will be treated as one piece for things like materials and coloring.