Removing Azure AD Connect With PowerShell.
If you’ve run into a situation where Azure still thinks it should be syncing Active Directory with an on-premise server, but that server is long gone, read on.
It has happened to me twice. In each case, it was a test scenario with a Windows server 2016 VM that was syncing to an Azure account that also had an Office 365 tenant attached. In short, AD Connect on the Windows Server stopped working. After several attempts (suggested by Microsoft) to remedy the situation (which included rolling back to a backup and a reinstallation) failed, I decided it was time to abandon the server as my testing was finished anyhow. Doing so, of course, leaves the Azure and Office 365 side wondering what is going on with sync. When you find yourself in this situation, you’ll deal with routine EMail reminders that AD Sync is unhealthy or has failed. Your Azure and Office 3655 online management portal will also display notification messages to inform that Sync has failed.
On Thursday, 10 May 2018 19:19:13 GMT, Azure Active Directory did not register a synchronization attempt from the Identity synchronization tool in the last 24 hours for tonymoreira [tonymoreira.onmicrosoft.com].
You can troubleshoot this issue by running the Directory Synchronization troubleshooter on the server that has Azure Active Directory identity synchronization tools installed.
The Azure Active Directory Team
So, if the server is not operational, how do we remove AD Sync?
The answer is to use PowerShell.