Sometimes its hard to uninstall SEP client if uninstall password is lost or SEPM is down.
In such cases you may follow these steps
Start – Run
type smc -stop ( If it prompts for password; navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Symantec\Symantec Endpoint Protection\SMC, delete the smcexit key and then type smc -stop)
Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Symantec\Symantec Endpoint Protection\SMC
look for smcinstdata key; delete it
go to add/remove program and uninstall the client..
I know its simple procedure; but sure will help few :)