Whenever you insert a new shape into a PowerPoint slide, you can see that it is filled with a solid color and has an outline by default (this may differ depending on the Theme applied to your presentation). You can remove the fill of the shape as well as the outline. In this tutorial, we’ll learn how to remove an outline from a shape so that it only includes a fill without any outline. Whatever you do, make sure that you either remove the fill or the outline because if you remove both, then your shape will no longer be visible.
Remove the outline from any shape in PowerPoint 2013 for Windows.

