Those are extensions lines which are set in the style in SketchUp. Evidently you used 3D Text to label the rooms and other parts. You can update the style for the scene in SketchUp to either have shorter extensions or turn them off altogether.
Note that since you have modified the view in LayOut, the change to the style won’t be displayed until you reset it back to the original view (Last saved SketchUp View). You really should be creating scenes in SketchUp to use for viewports in your LayOut project and you should not be opening the viewport to zoom or otherwise change the view. This creates the modified scene and disconnects the viewport from the scene in SketchUp.