tion can be, at the earliest, the date the application is submitted to the Student Office, or a future date (at the latest, the end of the semester). Retroactive de-registration is not possible. When choosing [...] choosing the date of de-registration, please note the following: In the case of transferring to another university, it is generally advisable to indicate the end of the semester as the de-registration [...] date, since enrollment at the new university usually takes place at the beginning of the following semester. If the degree program is ending for other reasons before the end of the semester, it is recommended
https://www.uni-rostock.de/en/study/study-organization/at-the-end-of-the-studies/exmatriculation/