To delete a wireless network connection
1.Right click on the network/wireless icon in lower right of your screen, then choose "Start Network and Sharing Center."
2.In the Tasks pane on the left side, click Manage wireless networks.
3.Right-click the connection you want to delete, and then click Remove network.
4.In the Manage Wireless Networks - Warning dialog box, click OK.
Then reconnect to your personal wifi network.
Is Comcast your provider? If so, you're basically using the 'public' connection that Comcast is installing everywhere.
You can disable it in your account settings...