Unable to remove a computer and user

Hi,

  for weeks I'm unable to delete a user and his computer from my subscription to Office365 Home. Last week I spent 3 hours with Microsoft tech. support on the live chat with remote session and on the phone - they were unable to resolve it. Promised me to call/email back once they find a solution, but they never did. The error can be seen on the screenshots below:

And when removing the user:

Did anyone experience this problem and found a solution?

Thank you for any help.

Marek