Remove Downed Exchange Server from First Administrative Group

Remove the exchange server from the First Administrative Group first.

First if you haven't already promote the new exchange server as the master: go to Exchange System Manager > Administrative Groups > First Administrative Group > Routing Groups > First Routing Group > Members Right click your new server and click "set as master"

To remove the old exchange server go to Exchange System Manager > Administrative Groups > First Administrative Group > Servers. Right click the old server go to All Tasks > Remove server

if you get an error like this

    The Server "SERVERNAME" cannot be removed because:
-One or more users currently use a mailbox on this server. 
These users must be moved to a mailbox store on a different server 
or be mail disabled before uninstalling this server.
Facility: Exchange System Manager
ID no: c103f492
Exchange System Manager

Then Open AD and do a search for all users who have Exchange Home Server attribute set to the dead Exchange Server. Remove Exchange mailbox association if you find any users using the old server.

If you cannot see administrative or routing groups then: Right click your domain (exchange) container (THE HIGHEST LEVEL) go to properties check off the administrative views. "Display routing groups" and "Display administrative groups"

Finally: Delete all the old DNS records for the old server as well as any DHCP records then simply delete the old server from AD this is assuming you were able to transfer all the Schema roles.

Hope this helps.

Just delete the old server. The new server should not exist in both places, just its current location.

It doesn't matter where you run adsiedit from.