1.If the diagram is in a document or a worksheet, double-click on the diagram to activate it.
2.Select the lines in the curve that you want to change; for instance, this might be the connection line of a curve, the grid line of a surface chart, or the border of columns. Press the CTRL key to select several items. Press the ALT key to select all items of a particular type.
3.You can set the color of the border lines by selecting a line color with Format[Lines] > Color. To remove a connection or grid line, select No Color. You can change the line style and width with Format[Lines] > Style and Format[Lines] > Width. Change the transparency with Format[Lines] > Transparency.
Notes
A line style cannot be selected for column borders.
The border around 2D columns cannot be turned off.
The border lines of individual columns cannot be changed because only the entire curve can be selected.