Hi
1. To remove the ESXi/ESX host from vCenter Server:
Click Inventory in the navigation bar, expand the Inventory as needed, and click the appropriate managed host.
Right-click the managed host icon in the inventory panel and choose Disconnect (wait for the task to complete).
Right-click the managed host icon in the Inventory panel and choose Remove.
Click Yes to confirm that you want to remove the managed host and all its associated virtual machines.
2. To add the ESXi/ESX host to a new vCenter Server:
Connect the vSphere Client or vSphere Web Client to the new vCenter Server.
Click Inventory in the navigation bar.
Expand the Inventory as needed, and click the appropriate datacenter or cluster.
Click File > New > Add Host.
In the first page of the Add Host wizard, enter the name or IP address of the managed host in the Host name field.
Enter the username and password for a user account that has administrative privileges on the selected managed host.
Click Next.
Thanks
Sakthivel