Not in this case, where I do not have a groundplane. The actual problem is, where a few atoms cast shadows on other atoms. (It is not an option to just move or rotate the molecule or part of it.)
In general: How to get objects to not cast shadow and/or not receive shadow?
If you use the Rhino 6 Rhino Renderer, these shadow casting and receiving object properties will work. Alternately, you can use a Rhino 6 Custom material and check self-illumination in the advanced settings for it. This will allow the Raytraced display mode to be used as well without the objects receiving shadows.
I know this was years ago and not sure if there is a feature to turn off shadows yet, but if you just want to get rid of the shadow on the ground just create another object and drag the object you want to render high above the other one so it is clear from casting a shadow on the ground.