uninstall instance of sql server

I have installed sql server 2008 r2 express by using configuration file in my application which requires sql server to work.So i created new instance using configuration file.The sql server install is done in quiet mode. Now i want to know how can uninstall the instance by using command line or configuration file?

I saw the link  stating about uninstall parameters. But the example command looks like 

Setup.exe /Action=Uninstall /FEATURES=SQL,AS,RS,IS,Tools /INSTANCENAME=MSSQLSERVER

here what is setup.exe? Is it sqlservr.exe installed in theinstall path? I tried to use that exe ,when i run command it showed balnk message with an error symbol