Hi,
There is indeed a left, right, up and down in regards with the drawing origin (0,0)
Completely at the left does not exist as the drawing plane extends from almost -infinity to +infinity, horizontally and vertically.
Almost, because infinite plus or minus something is again infinite making things impossible to represent.
Again, Layers have no position in the drawing.
A layer is a CAD concept, not an object.
You can’t move a layer to another position.
Entities may all be move to align their leftmost point with for example the Y axis.
But that would scramble up your drawing as there is no inter-relation between individual entities.
You can also offset all entities by an amount so that the leftmost point sits at Y=0.
Again that would require a custom Command Line script. 
Regards,
CVH