If one removes the trackball controller while the trackball info element is visible it will remain on the chart.
Steps to reproduce:
1. Add a chart to a form
2. Add series and data points 
3. Subscribe for the chart MouseClick event 
4. In the event handler change the value of the chart ShowTrackball property (from false to true or vice versa)
Start the project and click several times on the chart. You will see that trackball info elements will remain on the chart.