You cannot migrate mailbox '{0}' off of Office365 while the mailbox has a connected account enabled. To successfully remove ...

You cannot migrate mailbox '{0}' off of Office365 while the mailbox has a connected account enabled. To successfully remove the connected accounts, run the following command: 'Get-Subscription -Mailbox MailboxID -AggregationType All | Remove-Subscription'. Once this has successfully completed, you can attempt to migrate the mailbox again.