Removing Edge server

[neonetman]

Now we have the majority of our mailboxes on O365, and our MX records set to O365 I'm looking at removing our Edge server, and routing traffic for those last few on-prem mailboxes direct from O365 to the main Exchange server.

 

I've tried just changing the SMTP route on the firewall to point to the internal Exchange server, however nothing seems to hit the queue on there. Is there something else I need to do to remove the Edge server to ensure the Exchange server can receive messages?