Dear  Experts,

I have setup one more Role i.e. Mailbox Named Mbox in addition to move old Mailbox i.e Mbx in exchange 2010, all the Mailboxes have been moved to Mbox while Public Folder & OAB has also been relocated to this New Role.

Kindly let me know, at this stage, is it safe to remove the OLD Mailbox Role i.e. Mbx with its DATABASE ? tell me the best practices to remove it ?

Waiting for quick reply, please.

If you try to uninstall Exchange from a server it goes through several prerequisite checks and will tell you if the server is still in use for some things so go ahead and try that.

If it fails the prerequisite checks post back with the details

See the error and suggest me. It should be kept in mind removing this Old Mbx Role should not impact the performance of existing Mbox Role. Thanks in Advance :)

While I can't see the entire error, it looks like there are still some mailboxes and public folders configured for the old server.   Run through the commands in the error (which are actually really good) and try the uininstall again.  

there must be some arbitration mailbox and they must need to be moved to the new mailbox else you won't be able to uninstall this server.

read this article

http://blog.chrislehr.com/2009/10/exchange-2010-what-is-arbitration.htm

Hi,

As they mentioned and depending on screenshot, please ensure all mailbox database and public folder database have been moved to other mailbox server. Please run below command to double check:
Get-mailbox | Where {$_.Database EQ Mailboxdatabase} | Select Identity,Database
Get-PublicFolderDatabase Server Mbx

If everything works fine, please try to shut down Exchange server for serval days testing to ensure everything works fine before remove this server.

Best Regards,
Allen Wang