With Mint 13 and Ubuntu 12.04 the newest NetworkManager can cause a situation where you cannot edit or disconnect. The solution is to downgrade NetworkManager.

1. Download network-manager-gnome_0.9.4.1-0ubuntu2_i386.deb for 32-bit system or network-manager-gnome_0.9.4.1-0ubuntu2_amd64.deb for 64-bit system.

2. Downgrade Networkmanager via command line
cd /path/the-package.deb (eg. network-manager-gnome_0.9.4.1-0ubuntu2_i386.deb)

sudo dpkg -i network-manager-gnome_0.9.4.1-0ubuntu2_i386.deb ## for 32-bit
.. or

sudo dpkg -i network-manager-gnome_0.9.4.1-0ubuntu2_amd64.deb ## for 64-bit

3. Prevent upgrading the package

sudo apt-mark hold network-manager-gnome