Scripting

I think that more details would be helpful to properly answer your question.
For now, I'm assuming you have executed an MSI uninstallation (or MSI based setup.exe) and on this particular machine you received 1605 which means 'This action is only valid for products that are currently installed.", so the MSI wasn't there what in general is a success for removal action - Exit Code = 0 (SUCCESS).

MSI Exit Codes:
https://docs.microsoft.com/en-us/windows/desktop/msi/error-codes - rad33k 5 years ago