How do I unhide and remove disk mounts from Login Items? Some time back I added some network disk mounts as Login Items for my MacBook Air (Mountain Lion).

When I'm away from my network, though, I'm constantly bothered by warning boxes saying "Can't connect" to those mounts.

I went to my Login Items screen, and rather than deleting them, I hid them. I failed to understand the +/- buttons and the checkbox.

Now I can't find a way to "unhide" those disk mounts from my Login Items, and successfully remove the automatic mounts.
As shown in the following image, you can remove Login Items by selecting them (highlighting them) and clicking the "-" button. Hiding an item (by selecting the check box) in Login Items means that it is opened, but hidden.