Exchange 2010 Retirement

Hi Experts.  

We recently moved to a hosted Exchange service and it is 100% not connected to our on-premises Exchange or active directory.
I'm in the process of retiring our on-premises Exchange and am making great progress.  
Before I move forward with the next step, I wanted to check with the community and see if there is anything I'm missing.

I have 1 Mailbox Server and 2 CAS servers left.  
There is 1 Mailbox DB left and it does NOT contain any more user mailboxes - all disabled and retention has passed.
I do see a single entry under Recipient Configuration | Mailbox and that is the Discovery Search Mailbox bound to the single remaining Mailbox DB.  That's it.
Furthermore, under Organization Configuration | Mailbox, I see the 1 Mailbox DB AND Public Folders (which were never used).

Question # 1- Can I go ahead and simply uninstall this last Mailbox server since it only has that Discovery Search Mailbox tied to an otherwise empty first mailbox database and an empty public folders db?  I'm worried about missing some pre-step and getting into a messy situation mid-way through the uninstall of this last Mailbox server.


For the 2 CAS servers, there is a CAS Array defined in DNS (no load balancing being used)

I assume I can simply retire the CAS array and then uninstall gracefully (CAS2 and then CAS1).

Any other special care when I uninstall the final Exchange server (CAS1) from the organization?