How to: Turn off all gridlines in a chart.
Solution:
Select the chart and select the 'Insert' menu and select 'Gridlines...'. Clear the appropriate check box(es).
1) Select the desired chart.
a) If the chart is embedded on the worksheet, double-click on the chart. (A striped border with handles appears around the chart.)
b) If the chart is on a separate chart sheet, click the tab for the chart sheet and double-click on the chart. (A striped border with handles appears around the chart.)
2) Select the 'Insert' menu and select 'Gridlines...'. (The Gridlines dialog box appears.)
Gridlines dialog box
3) Clear the appropriate check box(es).
NOTE: Gridlines for the Category (X) axis are vertical. Gridlines for the Value (Y) axis are horizontal.
