Flash MX 2004.
shape.deleteEdge(index)
index A zero-based index that specifies the edge to delete from the shape.edges array. This method changes the length of the shape.edges array.
Nothing.
Method; deletes the specified edge. You must call shape.beginEdit() before using this method.
The following example takes the currently selected shape and removes the first edge in the edge array:
var shape = fl.getDocumentDOM().selection[0];
shape.beginEdit();
shape.deleteEdge(0);
shape.endEdit();