Use the eraser tool to delete objects from the EER Diagram canvas. Change the mouse pointer to the eraser tool, then click the object you wish to delete. Depending upon your settings, the delete dialog box should open, asking you to confirm the type of deletion.

To activate the eraser tool from the keyboard, use the D key.

You can also delete an object by selecting it and pressing Control+Delete or by right-clicking it and choosing Delete from the pop up menu.