In Major Grid--Ticks or Minor Grid--Ticks, specify tick settings:
To hide tick marks, deselect Visible.
To change the tick mark color, choose Color, then use the color picker to select or create a color. For more information about using the color picker, see How to set the chart background color.
To change where the tick marks appear on the axis, in Style, select one of the following options:
For a horizontal axis, select Across, Above, or Below.
For a vertical axis, select Across, Left, or Right.