Consolidating RDS license servers

Hi,

We currently have a 2003R2 server providing TS licensing for 2003 servers, a 2008R2 server providing TS licensing for 2008 servers and of course 2012 server providing RDS licenses for 2012 servers.

I believe that 2012 RDS licensing server should be able to manage CAL's for all of the previous versions of Windows mentioned here, so I was just wondering if someone could point me in the direction of how to remove the licenses from the other servers and move them onto the 2012 server if possible.

Thanks in advance!