find -iname "*-flat.vmdk" -mtime +7 -ls
you could identify vmdk files older then 7 days that have not been modified and are either off or orphaned.
or
find -iname "*-delta.vmdk" -mtime +7 -ls
to find old snapshots

Double check the version of the VirtualCenter Agent:
# rpm -qa grep vpxa
(For Example) VMware-vpxa-2.0.1-32042
To stop mgmt-vmware:
# service mgmt-vmware stop
Stopping VMware ESX Server Management services:
VMware ESX Server Host Agent Services [ OK ]
VMware ESX Server Host Agent Watchdog [ OK ]
VMware ESX Server Host Agent [ OK ]
To stop vpxa:
# /etc/init.d/vmware-vpxa stop
Stopping vmware-vpxa: [ OK ]
Uninstall [...]