Unable to remove email address from office group

[whomean]

Hi,

i am trying to convert an Office 365 Group into regular shared mailbox. I know there is no simple way to do that. I have a group with email address it @domain.com, I have change this address from Microsoft 365 admin center to it_group @domain.com, I also removed the old email address from aliases but I still cant use this address as address for new shared mailbox. In Exchange Online PowerShell when I use:

Get-EXORecipient -ResultSize unlimited | Where-Object {$_.EmailAddresses -match "Email address removed"}

I get result with my Office 365 group and there are two addresses visible: it @domain.com and it_group @domain.com.   Is there a way to unlink address Email address removed  from office 365 group?

P.S. I the past the address it @domain.com was used  as standard shared mailbox but i somehow managed to use it to create office 365 group. Now I want to use this address back as shared mailbox.

[#2]

Something fishy is happening here, I tried playing with the aliases for one of my group and few minutes later, the original set of alias was restored. I'll try poking around more, in the meantime I'd suggest you open a support case.