Remove Classic EAC Organization Add-ins?

Hello,

Does anyone know how to remove the organization add-ins that were deployed with the Classic Exchange Admin Center? Now that the "classic view" is no longer accessible, our tenant shows a 400 Bad Request error when trying to go to "https://outlook.office.com/ecp/".

This org add-in is pushed to all mailboxes by "organization administrators", and as far as I can tell, there isn't a way to remove the add-in. This legacy add-ins are not visible in the new "Integrated Apps" in O365. I contacted Microsoft Support but the support agent got to the point where he was having me run PowerShell commands to check the registry to see if it was "installed as a program on my computer", and that's when I knew he had exhausted his support resources. 

I can see the app if I execute: Connect-ExchangeOnline as a Global Admin & Tenant Admin (Exchange Online Role) and then run the Get-App | select DisplayName, AppID cmdlet.

If I try to remove it Remove-App -Identity <AppID>, then I see a:
Write-ErrorMessage : |Microsoft.Exchange.Data.ApplicationLogic.Extension.OwaExtensionOperationException|The app "Alert" is managed by organization administrators and can't be uninstalled by end users.

If I check the Exchange Online roles, I am in the TenantAdmins_3744d role, which states that "it will be a member of the Organization Management role group and will inherit the capabilities of that role group".

So far I have no way to remove this old add-in which normally was installed/uninstalled through Organization > Add-Ins in the Classic (Legacy) Exchange Admin Center.