Nice title huh? There are admins in the world that have installed a Central Administration Site because they had a Central Site in ConfigMgr 2007 and they thought they needed one now also. Most of the organizations that use ConfigMgr 2012 do not need a CAS at all since for instance a single Primary Site can support up to 100.000 clients. While writing a chapter about the migration feature for an upcoming ConfigMgr 2012 R2 book, I came across a scenario that would allow you to migrate your ConfigMgr 2012 hierarchy to a single Primary Site. So if you unnecessary made your ConfigMgr 2012 environment to complex by installing a CAS you are now able to easily move your hierarchy to a single Primary Site using the migration feature. Look here for some information about when to install a CAS.
Read the complete blog here:http://configmgrblog.com/2013/07/24/want-to-get-rid-of-your-configmgr-2012-central-administration-site/