If for any reason you couldn’t delete it, you can use a clipping mask to hide the shadow. First copy the circles you want to keep then paste on top of the original graphic. Next use pathfinder merge those circles, so they are one path. Finally, select the merged path and the original graphic then create clipping mask. You should hide the shadow successfully. If nothing or just one circle is shown, double check these steps: 1. You have merged all the circles path. 2. The merged path is on top of the original graphic.