First, determine how it manually uninstalls.
Review the registry on a machine that has Symantec Antivirus installed on it.
Navigate to:
HKEY_LOCAL_MACHINE\SOFTWARE\MICROSOFT\ WINDOWS\CURRENT VERSION\UNINSTALL registry key and locate the subkey dealing with uninstalling Symantec Antivirus.
For version 10.0 it is {BA4B71D1-898E-4306-AE87-8BA7A596F0ED}
The command to manually uninstall with for this version would be:
MsiExec.exe /norestart /q/x{BA4B71D1-898E-4306-AE87-8BA7A596F0ED} REMOVE=ALL
Symantec typically prompts for an uninstall password. This can be resolved by using the registry editor to modify the key:
"[HKEY_LOCAL_MACHINE\SOFTWARE\INTEL\LANDesk\ VirusProtect6\CurrentVersion\AdministratorOnly\Security]"
Set the values "LockUnloadServices" and "UseVPUninstallPassword" to zero. That will suppress prompting for uninstall password.
Obtain PSEXEC from Microsoft Sysinternals and install on the machine you are working from. Then execute the following subsituting the key for the particular version you are removing.
psexec \\computer_name MsiExec.exe /norestart /q/x{BA4B71D1-898E-4306-AE87-8BA7A596F0ED} REMOVE=ALL
NOTE: Symantec's uninstall leaves a lot of registry keys and files on a computer after "uninstalling" the product. In fact, you will not be able to reinstall the product after uninstalling due to the left overs. To completely remove all remnants of Symantec Antivirus or Norton Antivirus, you will need to acquire a copy of Symantec's CleanWipe utility which is a secured download from Symantec. You will have to call their support team to obtain this utility.