Select the chart element.
Click the Layout tab under Chart Tools.

Click the Gridlines button,
point to Primary Horizontal Gridlines, Primary Vertical Gridlines, or Depth Gridlines (3-D charts)

Click None or Major Gridlines or Minor Gridlines or Major & Minor Gridlines

5.9.Chart Gridlines |
| 5.9.1. | Change Chart Gridlines: None or Major Gridlines or Minor Gridlines or Major & Minor Gridlines |  |