How to Manually Remove a Static IP Address From a Registry
You might not think too often about your Windows registry, but it is one of the most important pieces of your operating system. If the registry isn't functioning properly, chances are that your system performance will be limited, or you may not be able to use your computer at all. You can modify your system registry, but take care in doing so. Remove a static Internet Protocol (IP) address from the Windows registry by manually editing the Registry Editor.
Type "Regedit" (without quotation marks). The Registry Editor appears.
Open the following path in the Registry Editor: HKEY_LOCAL_MACHINE\SYSTEM \CurrentControlSet \Services \Tcpip\Parameters\Interfaces.
Choose the network interface for which you want to delete the IP address.
Click that network interface to open it.
Right-click the IP address key and select "Delete."