You can find the product code by perusing the registry from this base key: HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionUninstall . Press F3 and search for your product name. (If it’s a 32-bit installer on a 64-bit machine, it might be under HKEY_LOCAL_MACHINESOFTWAREWow6432NodeMicrosoftWindowsCurrentVersionUninstall instead).
Finally, you can find the product code also by using PowerShell:
get-wmiobject Win32_Product | Format-Table IdentifyingNumber, Name
when you found the Guid ID you can use msiexec to uninstall the application
msiexec /x {A4BFF20C-A21E-4720-88E5-79D5A5AEB2E8}