"Locked" Google Assistant integration after failing to install

Hey guys. I was trying to install the mentioned integration. I failed (of course :grin:) but nothing special yet.
When getting to the OAuth page i got an error.


Obvious i entered the wrong data.
The problems appeared only know. Wanting to try again the install, i am getting directly the same error window.
The integration does not appear between the installed ones so there is no possibility to delete it for begining again from scratch.
How, on Earth, can i solve this problem?