Content of this post is not recommended to be used unless you do not have backup of your edge transport configuration. All steps below are tested in a specific environment and may not apply to your environment. Do it at your own risk!!
I would recommend you perform recovery of your edge transport servers Understanding Edge Transport Cloned Configuration and use Cloned Configuration method and this content must be used as a last resort.
While Exchange 2013 is out to the market and a lot of deployments are happening around, Edge Transport role of Exchange 2010 still deserves its own importance since Exchange Server 2013 does not have any Edge Transport Role of its own version.
Today, I was working on recovering an edge transport server role which did not go well with recovery. Finally, a call was made to remove this edge transport role. The only hurdle was we could not install a fresh OS on this box since the servers are located in a remote data center. The only option was to remove the edge transport role manually and clean up the OS so that it can be used to reinstall edge transport role
So here is how you do it:
Stop Exchange Services (Leave them in whatever state they are if they do not stop)
Remove Registry Entries (Note! You must perform registry backup every time you change anything in registry)
- Open Registry Editor
- Browse to HKLM\SOFTWARE\Microsoft
- Locate registry key named ExchangeServer
- Delete the key ExchangeServer
- Browse to location HKLM\SYSTEM\CurrentControlSet\Services\
- Locate registry keys starting with MSExchange e.g. MSExchange ADAccess
- Remove all registry keys starting with MSExchange
- Browse to your exchange installation location. Typically at C:\Program Files\Microsoft\
- Delete the folder Exchange Server. If you are scared of deleting it, you can simply rename it to Exchange Server.OLD
Remove LDS Instance
- Open Command prompt with elevated privileges
- Browse to location C:\Windows\ADAM
- Type ADAMUninstall /i:MSExchange and hit enter
- Click Yes on both the dialog boxes appearing after you hit enter
- Restart the server
While you reinstall the exchange edge transport role, you may receive some weird errors at the first time. This is expected to happen when you remove everything in a crude way.
- Locate the registry key HKLM\SOFTWARE\Microsoft\ExchangeServer\V14\EdgeTransportRole
- Delete the WaterMark string from the right hand side pane of registry editor
- Browse back to location HKLM\SOFTWARE\Microsoft\ExchangeServer\V14\
- Right click and create a new key named Transport
- Create one more key named Pickup at HKLM\SOFTWARE\Microsoft\ExchangeServer\V14\
- Re-run exchange edge transport setup
Your edge transport role should be back to operation and you can create a new edge subscription with Exchange 2013 mailbox or Exchange 2010 HT servers.