If you leave Austria and give up your residence here, you must cancel your registration within three days after you have left your home. The authority responsible for this withdrawal is the issuing authority for which the application has been made. The cancellation must be made in the municipality responsible for the main residence.
In Vienna it is possible to opt out of a Viennese residence in any "Wiener Meldeservice" - independent of the residential district.
Information provided by EURAXESS Austria