An illustrator has a natural tendency to include too much in a composition. When this fact is clear, he has an equally natural reluctance to remove portions of a rendering over which has worked so diligently. Renderings are often improved significantly by some judicious "cropping" - removing areas that detract from the center of interest or interferes with the effectiveness of the composition.
None of the rendering actually needs be cut away or destroy. It may be crop differently (non-destructively) for another use, so keep the entire rendering and crop in a non-destructive way.