You can only delete links while you are in the DataPA SetUp screen.  Please Note, you can not delete a Link which has been used in any of your Subjects.

Select the System you wish to delete by clicking on its name in the tree view.

Click on the 'Delete' Icon on the Ribbon.

Note: There is no warning on the delete of a Link, unless the link is in use by a subject.

Remember to Save your changes.