Firstly here's a clean sphere you can download.
To get a clean sphere without shadows follow the following steps below:
1. To get rid of shadow under the sphere, unclick shadows box in propreties tab.
2. To get rid of shadow that appears at the top of bottom of the sphere point your light to the center and unclick the eye icon next to sphere material in the 3D tab.
Here is the poster i made after following the tutorial.
Thanks to tom for a great tutorial !