If you live in Tanzania, possess another citizenship in addition to German citizenship, and, for certain reasons, wish to renounce your German citizenship, you must file an application through the German Embassy in Dar Es Salaam.
Further information as well as the application form (in German) can be found here
If you wish to renounce your German citizenship, please get in touch with the Embassy in Dar Es Salaam via firstname.lastname@example.org.
Your application will be forwarded by the German foreign mission to the German Federal
Office of Administration in Cologne, Germany. If renunciation is approved, a renunciation certificate will be issued to you. It will be handed over to you by the foreign mission. The renunciation does not enter into force until you accept the certificate.