DBAs don't need local administrative access to the servers if the responsibilities for said DBAs are solely within SQL Server. Notice I said solely, as in nothing outside of SQL Server. And that's a key point: what are the expected responsibilities? In my organization there are a lot of things outside of SQL Server our DBAs are responsible for, meaning the removal of such rights would render our DBAs incapable of doing the job they've been assigned to do.

If you give us an idea of what all your DBAs are expected to do, we can probably give you a better of idea of what rights are needed.