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.
If I want to enable failover
clustering for both Exchange 2010,
ensure zero downtime. What are the
steps?
RTFM.
First, failover cluster DOES NOT GIVE ZERO DOWNTIME. Bad news, isn't it - happens because you did not read the documentation. Failover cluster will start exchange / a VM on another server if the first fails. It takes some time (seconds) to realize the original system is down, plus the time it takes for the system to start (larger for a VM), so while the time is small, IT IS NOT ZERO DOWNTIME.
Second, Exchange can do that a lot better WITHOUT a failover cluster. Exchange has it's own cluster mechanisms that can work with multiple data copies... which means one less thing that can g o wrong (corrupt files in a node crash), so it is (a) superior to failover cluster and (b) faster in switching.
So, I sgugest getting your requirements straight, and then using Exchange integrated mechanisms to ensure uptime.
Best Answer
The only real reason you'll need to use Windows Server 2008 R2 Enterprise edition for Exchange is if you want to use the high availability DAG features of Exchange 2010.
The requirement of the Enterprise edition of the operating system is because DAGs use pieces of Windows clustering to do their thing, which is not available in the Standard edition.