There is no Dial-up Networking per se in Windows 2000. You simply remove and recreate the connection; it will automatically rebind to TCP/IP. Note: Never remove TCP/IP; you cannot get it back easily.
To remove and recreate the connection:
Click Start, select Settings and click on Network and Dialup Connections.
Right click the connection you want to remove and select Delete from the menu.
Recreate the connection by clicking Make New Connect. Refer to this page for how to make a dial-up connection using the wizard.