When you open Microsoft PowerPoint, the slide thumbnails appear in the left-hand pane by default. PowerPoint lets you hide, show, or even change the size of those thumbnails. Here’s how.
Manipulating Slide Thumbnails
Everyone has a different working style. Some may prefer to keep the slide thumbnails to create an outline or easily navigate between slides when making edits. However, some might find them distracting or intrusive and, as such, would like to hide or decrease their size. Both are relatively easy to accomplish.
Go ahead and open PowerPoint. By default, you should be in PowerPoint’s “Normal” view mode. If you’re not, head over to the “View” tab and click the “Normal” button.
Once in Normal view, the slide thumbnails will appear on the left-hand side of the window.
To decrease the size of the thumbnails, click and drag the splitter bar to the left.
from How-To Geek http://bit.ly/2YzQdna