Exchange 2013 SP1 Uninstall to Migrate to Server 2012 R2

Hello,

We have one Exchange 2007 Server and we want to migrate it to Exchange 2013.

We installed three Exchange 2013 SP1, the first that we installed was in a Windows Server 2012 and the other two Windows Server 2012 R2.

Now, we want install another one in Windows 2012 R2 (same name, same IP) , because DAG doesn't work with 2012 and 2012 R2.

But my doubt is:

What are the steps to remove the Exchange in Windows 2012? Is so easy like uninstall from Control Panel -Uninstall a Program... or we need to do something more to remove the actual Exchange completly from Active Directory.

Thanks in advance.