By default, PowerPoint ends your presentation with a black slide. If you would rather it end with your final slide, follow these steps and be rid of the black slide.
1. Click the Office Button.
2. Click PowerPoint Options.
3. In the left pane, select Advanced.
4. In the right pane, go to the slide Show section.
5. Uncheck the End with black slide checkbox.
6. Click OK.
The presentation will now end with your final slide.