You could use conditional visibility on the table row that contains the link widget.
$obj/Link != empty
).Now you can configure the row to appear when the link has a value, and disappear when it does not.
See this page for more information about conditions.
Hope this helps!
Edit: In 2.4, the condition settings are somewhat hidden. You should right-click a table cell, click the 'Select row' option, and then right-click again. Now the option 'Set conditional formatting...' should appear. Click that to get to the condition settings screen.