Please see #4:
I have already donwloaded the latest version and deinstalled the former one.
Result: everything is gone now....
Of course did I download the EPUB (Incl. DRM) with ADE also. But this is destroying the nice formating of the official kepub file.
BTW: to use calibre you have to remove the DRM which is still illegal... I wont do this.
Also do I have the problem on my PC not on the phone.