Click the Features | Edit Polylines | Break Polyline command or right-click a polyline and click Break Polyline to break the selected polyline or spline polyline into multiple polylines. The cursor changes to to indicate break mode. Click on the polyline or spline polyline in the location where the line should be broken. For the command to be available, a single polyline or spline polyline must be selected. Spline polylines are converted to regular polylines after being broken apart.
The new polylines retain the line properties from the original polyline. If the object name has not been changed from the default Polyline or Spline Polyline, the new objects are named Polyline. If the object name had been altered, the custom object name from the original polyline is retained for both new polylines.