The application can be made in writing or in person by appointment with the authority. By submitting the application, you must present facts and credibly demonstrate why you may be at risk to life, health, personal freedom or similar interests worthy of protection by providing information. Such forms are available, for example, at https://www.service-bw.de/leistung/-/sbw/Melderegister++Auskunftssperre+bewerbungen-4543-leistung-0.
Sources: