You can submit a request for a divorce or a dissolution of a registered partnership at the court. You need a lawyer for this. The court pronounces the judgment of divorce. Is the decision of the judge final (irrevocable)? Then you must report this to the municipality. As soon as the municipality signs the divorce in civil status, it is official.

You, your lawyer or your former partner must report the divorce within 6 months to the municipality where you were married. 

The central government provides further information on their website.