IntelliJ IDEA suggests two ways of deleting elements from diagram:

  • Remove node elements from view, while leaving the underlying source code intact. This option can be helpful, if you want to explore a certain group of nodes, and remove the unnecessary ones from view.
  • Delete node elements from project.
To remove elements from view
  1. In the diagram, select one or more elements to be deleted.
  2. Press ⌦, ⌫, ⌘⌫, ⌦, ⌫ or ⌘⌫⌦, ⌫, ⌘⌫, ⌦, ⌫ or ⌘⌫⌦, ⌫, ⌘⌫, ⌦, ⌫ or ⌘⌫Delete, ⌦ or ⌦Delete, ^ D, ⌦, ⌃D, ⌦ or ⌃D.
To delete elements from project
  1. In the diagram, select the element to be deleted.
  2. Use the Safe Delete refactoring (⌘⌦ or ⌘⌦⌘⌦ or ⌘⌦⌥ Delete, ⌥⌦ or ⌥⌦) to delete selected classes from project.