These lines show relations between objects. I think in your case these are parent-child relations, which means that in the bottom left corner there is an object (parent) that, if you move it, moves all the other objects (children) with it.
You can disable that these lines are drawn. Press N while your mouse is in the 3D viewport to bring up the Properties shelf. Then scroll down to display and disable
Alternatively you can activate
Only Render. Then anything that is not mesh data will be hidden, except for the transform widget.
If you also want to deactivate the transform widget look for the marked butten at the bottom of your 3D viewport:
Also have a look at the outliner window in the top right of your screen. It can tell you much about the scene: