Exchange 2010 Retirement

You can delete the discovery mailbox.
As a precaution before uninstalling I would turn off all exchange services and verify if you have any issues before hand.

Do not uninstall the role straightaway. Turn off your services first as Foxluv suggested and then after a few days, turn off your server for a week atleast and monitor all the processes which are dependent on email server. Once you see everything is working fine, you can uninstall the exchange server.

Remove SCP to ensure your internal client will not connect by SCP instead use the DNS/Autodiscover method.

Get-ClientAccessServer | Set-ClientAccessServer -AutoDiscoverServiceInternalUri $Null

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If you are not using on-prem anymore you can delete the arbitration mailbox by this command and uninstall Exchange from Add/Remove programs.  Stop the Exchange services for couple of days to be safe before uninstall.

get-mailbox -arbitration | remove-mailbox

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Please check this for more details
https://technet.microsoft.com/en-us/library/dn931280(v=exchg.150).aspx

Thanks

Thanks.  There is nothing utilizing Exchange in the building anymore.  The 2 CAS boxes have been off-line for the past 2 months so we are definitely at the point where I can remove it.  There is NOTHING using these servers and as noted above, all user mailboxes are long gone and even the mailboxes databases are all gone except for this last one which has nothing but the discovery mailbox on it.  

Taking that all into account, does it sound like I can just delete the discovery mailbox and do the uninstall from Add/Remove Programs?  

When done, I'll just have to deal with 2 CAS boxes.

@MAS....thanks.  Every single Outlook client in the building has had their Outlook profiles rebuilt to utilize the 3rd party hosted email system.  No one is connecting to the internal CAS defined in the SCP because I had the NICs of both CAS servers off-line for past 2 months.

Regarding the Public Folders, should I remove that database first or will the uninstall of my final mailbox database server remove it?

If your CAS is down for few 2 months you can uninstall it right away as CAS server is your client interface.

Regarding PF. EIther you move to cloud https://technet.microsoft.com/en-us/library/dn874017(v=exchg.150).aspx
or delete it before uninstalling.

Thanks

@MAS, thanks.  

We do not use Public Folders (never did on premises) and do not with our new 3rd party hosted environment so that should be all set.  I will remove the Public folders database before uninstalling.

For the Discovery Search Mailbox, should I right-click and choose "Disable" like I did for all the users OR should I right-click and do Remove (which will also remove the corresponding AD account I think).

If I right-click and do disable to get rid of the mailbox, will the Exchange uninstall remove the DiscoverySearchMailbox account from AD?

*** UPDATE ***

I am down to just 2 servers:

1 CAS Server
1 Mailbox Server

The mailbox server has 1 mailbox database and 1 public folder database.
The mailbox database points to the public folder database as it default
The mailbox database has no user mailboxes
The mailbox database still has a the discovery search mailbox
There are also 3 arbitration mailboxes still in existence

This is a simple single domain environment.  We do NOT use Exchange at all anymore and all I need to do is uninstall the final 2 servers.  

Since it will be difficult to award points to so many people who have contributed, I will award points to whomever can give me a clear path to take so I can get these final 2 boxes gracefully uninstalled.  

Which server should I uninstall first and what power shell commands should I run at this point.  

Thank you!!!

@Mas - thank you.

I'd like to delete the search mailbox gracefully from PowerShell or from within the EMC using either:
 
 Right-click | remove
 Right-click | disable

I'm leaning toward remove because I don't want the discoverysearchmailbox AD account lingering after the discovery search mailbox is gone.  Is this safe to choose remove?

Will the uninstall of the mailbox server remove all the arbitration users in Active Directory?

Interesting that you suggest CAS uninstall first.  When I installed the environment about 4 years ago, I recall reading the first role you should have setup is a CAS role.  Shouldn't I have the CAS also be the final server in the environment before completely removing Exchange.  Any harm in doing it that way?

Just checking back again...I won't have an opportunity to resume work on this until late next week and will post an update at that point.  Thank you.

I did it slightly different and had to search for more details, but MAS pointed me in right direction.