Importing Sketchup Make files into Blender - Problem with extra lines/edges

Importing in Blender files like SketchUp’s .dae or .skp cause problems like this (the picture isn’t from me, but it’s about the same problem):

Can you see the extra edges/lines? It’s a problem, because I want to work with textures and then export the Blender file to Cities Skylines. I don’t want to learn Blender, it’s not easy as Sketchup and I had tried and failed, but I want to use the Blender render and texture system (I learned that). I don’t want that edges.

Thanks in advance.