Delete MacOS Sierra Installer .dmg after Update
OS X Installer files are automatically deleted from Applications as part of the install process. Normally, it shouldn't need moving there, App Store ought to put it there directly as part of the download process.
They are very unlikely to have any 'related files' of the type that AppCleaner could find.

If you did want to keep a copy for the future, then you need to copy it outside Applications before running the Installer.