unable to delete a SP modern team site "The site can't be deleted becuase it's connected to office."

Hi everyone with the same problem.

I haven't read every link and solution so maybe my way to solve this issue was suggested and / or failed already.
But here is what helped me:
1. deleted site via share point admin center
2. because i wasn't able to permanently delete that site under "deleted sites" i deleted the office Group permanently via azure admin center
3. still, it wasn't possible to delete site permanently so i restored it. Got message that the office group couldn't be found so it will restore without group. Yes, fine
4. Finally, just as it emerged I deleted it again

5. now it was possible to delete it permanently.

Hope this will help people who still have this issue.