how to remove sql instances in sql server 2008 ?

Two days ago i installed sql server 2008. Name of the instance was "optima". Today in the morning I had to complete uninstall SQL Server and install again, but this time the instance name was "CDNXL". When I want to connect to sql server via SQL Management Studio I can still chose in field Server Name the old instance named "optima". How to remove that old instance. PLS Help.
greetings from Poland
Lucas

Go to View>Registered Servers and remove the old registration. Hopefully this cleans up the dropdown list.
Wrong suggestion, sorry - I got my "registrations" mixed up. The list is probably buried somewhere in the registry.