You can remove Auto Dial Names or Addresses through
the registry.To get a list with entrys saved by AutoDial open a
command prompt and type :

rasautou -s

To delete an entry from this list navigate to:

- HKEY_CURRENT_USER\Software\Microsoft
\RAS Autodial\Addresses

Within this key you can delete any TCP/IP address.Addresses can be
IP addresses,fully qualified domain names and NETBIOS names.

Note:If you are not confident using the registry use the common
way to remove Dial Up Connections through Network Connections
in Control Panel.

I checked this on my PC,but as i am not using a Dial Up Connection
the entry "Addresses" was missing.