Because a diagram and its underlying model exist independently, it is possible to delete a figure from the diagram without removing the attached element from the model.
For example, we might decide we do not want the diagram to show the link between the Librarian actor and the Adding a new book use case. To remove the link figure without removing the actual link between the elements, follow these steps:
To confirm that the link still exists (even though it is no longer shown), select Hide/Show Relationships from the Librarian figure's pop-up menu. You should still see the link listed as an existing relationship. (To restore the figure to the diagram, use the >> button to add it back to the list of shown relationships.)