Tap on the entry for GMX that you created when setting up
The FreeOTP app generates a confirmation code and displays it.
generated code expires after a certain period of time. After this time has
elapsed, FreeOTP automatically generates a new code that you can use if you
were not able to enter the previously displayed code on
Enter the code that is displayed by your FreeOTP authentication app.
Click on Continue.
You have successfully deactivated two-factor authentication.