Fill out the Antrag auf Exmatrikulation to terminate your status as a student at TU Darmstadt. You may find the form in TUCaN under Service> forms. Either state the exact date you wish to de-register or fill in the official end of the semester (SoSe: September 30th/WiSe: March 31st). Submit the form whenever you wish to de-register.
Once you receive the confirmation in your TUCaN Account under service > my documents, make 2 copies which you submit to the office of International Relations of TU Darmstadt and your health insurance company (this can also be scanned and sent per email). Keep the original certification – You will need it if you ever want to apply at a German University again.
If you are still taking exams or if you are taking exams from TU Darmstadt under the supervision of your home institution when you are back in your home country, you have to stay enrolled at TU Darmstadt. Furthermore, you cannot cancel your health insurance before you de-register. TK suggests writing the same date for de-registration as your departure date.
Your Semester ticket will expire directly after de-registration.