Too many group mailboxes are displayed

Good day

I have to preface this by saying I am logged into CRM as admin.

We had three group mailboxes active in CRM.
Now we have deleted two of them.

If I now go to Mails in the top menu and open my mailbox, I have the selection of the group mailboxes in the top right corner.
But there I see firstly 3 times the same group mailbox and secondly all group mailboxes that are no longer available.

How can this be cleaned up?

Are all mailboxes always displayed to me as admin?

Greetings Polymed