First thing you need to do is backup your Registry.
Next, change the HKEY_LOCAL_MACHINE\SOFTWARE\Symantec\Symantec Endpoint Protection\SMC\smc_exit_test from 1 to 0 prior to stopping the service.if smc requires a password
1. Stop the SMC service.
2. Delete the SmcInstData key located under HKLM\SOFTWARE\Symantec\Symantec Endpoint Protection\SMC\
3. Start the Symantec Endpoint Protection uninstall
Moving this thread to the Endpoint Protection forum for better visibility.