To Delete Diagram Objects
1. Select an object that you want to delete. Select multiple objects by using a selection rectangle around the objects that you want to delete or simultaneously hold down the SHIFT key and select the objects. You can also use an appropriate filter to select multiple objects for the selected filter. The selected objects are highlighted.
2. Click Edit > Delete. The selected objects are deleted.
* 
If you delete components that have wires routed to them, the Confirm Delete dialog box opens and you are prompted to take action on the connected wires. You can delete the attached wires or leave the wires as unattached.
3. If you have selected multiple items, clear the Apply to All Selected check box and click Apply in the Confirm Delete dialog box.
or
If you have selected a single item for deletion and right-click to select Delete from the shortcut menu.
4. To restore the deleted diagram objects, click Edit > Undelete or right-click and select Undelete from the shortcut menu.
* 
Deleted objects are restored only if you perform an Undelete operation immediately after a Delete operation.