cannot dectivate my 2nd licence 2017

I would like to deactivate my licence for SDL Trados Studio 2017 Freelance Plus, because after an upgrade of my system (notebook),  I would like to upgrade to SDL Trados 2019 Freelance PLus. (I have already bought this version and upgraded my PC (with the first activation) a couple of month ago.) However, I can neither deactivate the licence 2017 out of the program on my notebook nor can I deactivate this licence on the SDL website, because under *all licences* it is not displayed any longer.
Looking for some advice. Thank you :-)
Kristin