When you arrived in Munich, you will have registered at the Kreisverwaltungsreferat (KVR; Munich Registration Office). Before you leave, you should ensure that you also de-register there. Please do not forget to de-register. Failing to de-register could lead to problems if you decide to return to Germany at a later date.
You can de-register personally at the Bürgerbüro of the KVR or post the completed deregistration form to the following address:
Hauptabteilung II Einwohnerwesen Bürgerbüro
The required deregistration form can be downloaded at www.muenchen.de > Rathaus > Stadtverwaltung > Kreisverwaltungsreferat > Bürgerbüro or on location at the Bürgerbüro.