Select the chart element.
Click the Layout tab under Chart Tools.
Click Axes button
Point to Primary Horizontal Axis,
and then click None, Show Left to Right Axis, Show Axis without labeling or Show Right to Left Axis
Point to Primary Vertical Axis,
and then click None, Show Default Axis, Show Axis in Thousands, Show Axis in Millions,
Show Axis in Billions or Show Axis with Log Scale