German is a compulsory subject. You can only be exempted from the lessons and the exam if you have one of the following certificates:
Sprachdiplom der Kultusministerkonferenz Stufe II Test DaF with at least four points in each of the four parts of the test "Kleines Deutsches Sprachdiplom" or "Großes Deutsches Sprachdiplom" from a Goethe-Instituts "Zentrale Oberstufenprüfung" (ZOP) from a Goethe Institut C1 or Telc Hochschule C1