How to remove already removed AC devices?

Hello, I try to remove two empty rooms in my application, but it says:

"Error"
"This room cannot be deleted. It is still in use by a diffrent Netatmo-App.

Also I still see in my list of devices two old and removed devices:

https://home.netatmo.com/control/dashboard

Netatmo AC Controller ga87cd2
Netatmo AC Controller ga885cd

How can I remove these devices?

Kind regards

Axel