I think, but I am not sure you may clone the VMDK files via esxcli and create a new VM attaching these clones VMDKs into it separating'em into another VM directory
Making sure the VMDKs isn't in lock state and the VM is consolidated.
I think this KB maybe useful:- VMware Knowledge Base
Are you using vCenter?
If you are not connected to a vCenter, cloning is not an option for the version you're using.
As others have said, cloning via the GUI is only an option when 2 things are true:
1. Your host is being managed by vCenter Server
2. The GUI is connected to your vCenter Server