DFS replication role and SYSVOL replication

How does DFS role and SYSVOL replication related?

if we first setup the environment in domain functional level 2008 or higher, the SYSVOL replication will be using DFS by default without us adding the DFS replication role, right?

In test environment, I added DFS replication role, then did nothing.  But then when I try to remove the role, the error message shows "Before removing DFS Replication, remove this server from all replication groups"

May I know what to do to proceed to remove this role? 

Thanks