It’s easy to delete or rename templates by going into the Change Chart Type dialog box and selecting the Manage Templates button. This displays an Explorer window where you can right click on the template files stored there and rename or delete them.
If you delete a template that was the default chart type you will get an error whenever you attempt to create a default chart. That’s easy to fix. Just display the Change Chart Type dialog box and set a new default chart type as the 2D Column chart. That’s the normal Excel default chart.