How to remove the all link in child node?

The old nodelink remains.
How to remove the all child link in node ?

That is very odd looking. How did you get to that situation?

The normal behavior when one removes a node from the diagram is that the connected links are also removed. Exception: if you set http://gojs.net/latest/api/symbols/CommandHandler.html#deletesConnectedLinks to true.

The normal behavior when one makes a node not visible is that the connected links become not visible (but the node and links remain in the diagram).