Use SPFServerManager.exe with the /deletewcsite and /sn: arguments to delete a Web Client site from the server.
The following optional argument is available:
/forcedelete:[true|false] - deletes the physical directories of the site, as well as log files.
/samusername: - provides the administrative Smart API Manager user name for deleting the site from the server.
/sampassword: - provides the administrative Smart API Manager password for deleting the site from the server.
This example deletes the site named SPFClient.
SPFServermanager.exe /deletewcsite /sn:SPFClient
This example deletes all folders:
SPFServermanager.exe /deletewcsite /sn:SPFClient /forcedelete:true /samusername:sa /sampassword:1