We do not recommend to delete a temporary virtual machine directly in vSphere/Hyper-V. This may lead to artifacts in the web interface. Also, the backup from which the machine was running may remain locked for a while (it cannot be deleted by retention rules).
To delete a virtual machine that is running from a backup
The machine is removed from the web interface. It is also removed from the vSphere or Hyper-V inventory and datastore (storage). All changes that occurred to the data while the machine was running are lost.