A multi-pane chart can optionally have a button pane, a thin pane containing only a series of chart buttons, typically at the top of the chart. Normally the button pane is displayed without a title bar. If you right-click inside the button pane and choose Show Pane Title, the title bar will appear, telling you that this is indeed a "Button Pane"
Note the small rectangle at the upper left containing an X. Click on the X to delete the entire pane of buttons. Investor/RT will ask you to confirm before it deletes all the buttons.
If your button pane contains only one or two buttons you can achieve the same end result by simply deleting the buttons individually. Right-click on each button in turn and choose Cut (Delete). When you Cut (Delete) the last remaining button, the empty pane will be removed from the chart.