Is there a way to make Ubuntu "forget" a network connection? [duplicate]

Is there a file or something that holds the data for the internet connections?

In Ubuntu, take a look at the following folder: /etc/NetworkManager/system-connections/.

The files in here should contain the network connections' settings Network Manager has saved: network card used to connect to the network, SSID name, wireless key/passphrase, IP configuration method, etc.

Of course, the files can only be read as root. Using your normal account, you cannot open the files and read the settings.

The files cannot be deleted by another user than root. To delete a settings file, an administrator would execute the following commands in a terminal:

cd /etc/NetworkManager/system-connections
rm <filename>

where <filename> would be replaced by the actual filename. To delete all the settings files in one time, an administrator would use the * joker as the filename.

You can click on the Network Icon --> Edit Connections, this will let you delete previous Wireless or Wired configurations.