Can you provide more information on how these hosts are configured. Are all 8 hots under the same vCenter currently?
At a high level, if you are looking at separating them out into two different clusters under their own vCenters, You will have to remove one of the host, then install a new vCenter on it and then add it the host that hosts the vCenter into it. Then you disconnect the other three from the existing vCenter and move them under thew new one.
Abhilash B
LinkedIn : https://www.linkedin.com/in/abhilashhb/