I have a VM that was destroyed but the IP still pings.
It is likely the VM was unable to be stopped for some reason and will be shown on the 'Alerts' page.
Grab the identifier for the VM and go to the HV that the VM was on and run the command below:
virsh list | grep *identifier*
If the command returns nothing, then that VM isn't running on the HV. If the command returns something like below, then the VM is still running on the HV:
virsh list | grep hs4dfnrnz0u770
10 hs4dfnrnz0u770 running
Now, we can remove the running VM by running the command below:
virsh destroy identifier
virsh list | grep identifier should show nothing now, because it was removed.
Note: For XEN hypervisors for OnApp versions prior to 6.0 replace 'virsh' with 'xm' in the above commands.