If an item is in use somewhere within your company file, QuickBooks will not let you delete it. For example, if you have entered a shipping method on an invoice, QuickBooks will not let you delete that shipping method from the Ship Via list, until you remove it from the transaction.
Subitems: If the item you want to delete has subitems, either delete the subitems or move them to another part of the list. QuickBooks does not allow you to delete a list item that has subitems.
The Delete command changes to indicate the type of item you are deleting. For example, if you are deleting a name from the Employee list, the command becomes Delete Employee.