How can I remove Grid Line(hide selection border) in Donut chart.

Version 4

    I have created Donut Chart for one of Dashboard, When i hover over the chart, I would like to remove selection border lines from inside of the Donut chart. I have tried to remove from Formatting and shading but not been able to.

    I have tried with Formatting having all Lines to none,and Shading ( Shading it to white) . Please see attachment highlighted in yellow, I would like to remove the line when I hover over mouse.

    Attached is the sample workbook, it is in version 9.2