When it comes to grid lines there are only two options: on or off. You can make this election by going to the Edit menu option within the chart and selecting Global Chart Configuration. On the left side under "Charts" choose "Chart Colors". On the Chart Colors page the third option from the top will be "Hide gridline". Uncheck this box and click Apply to remove grid lines.
However, if you wish to have vertical grid lines without the horizontal ones, you can turn off grid lines and turn on "Intersection between trading days". This will give you a vertical grid line between trading days. To turn this option on, click the Edit menu option within the chart and select Global Chart Configuration. The first section will be "Display". Check the box that says "Intersection between trading days" and click Apply and OK.