You can delete diagrams on the Mapping screen.
Relational Migrator requires at least one diagram in your project. You
must have at least two diagrams before you can delete a diagram.
Click the name of the diagram in the Diagram Toolbar to display the
diagram.
Click the arrow button to open
the Diagram Properties pane.
The Diagram Properties pane displays the active diagram name and
notes.
A confirmation box opens.
Once you confirm that you want to delete the selected diagram,
Relational Migrator deletes the diagram. This step cannot be
undone.