One way to rename a VM's file and folder is to use Storage Migration, and migrate the VM to another datastore (after renaming the VM in the inventory).
Renaming just a virtual disk can be done from the command line using vmkfstools, e.g.
vmkfstools -E source.vmdk target.vmdk
(please note the upper case -E)
After renaming the .vmdk file (the command will rename the descriptor as well as the flat file), you need to either edit the configuration (.vmx) file, or change the VM's settings via the GUI to access the renamed virtual disk. In case you edit the .vmx file manually, remember to reload the .vmx after editing it (see e.g. https://kb.vmware.com/kb/1026043)
André