Run the following command to get a look at what you are importing
$ VBoxManage import /<path_to_.ova_file>/<vmName>.ova –dry-run
Pay attention to this line for target path. It should point to your new location for your Virtual machines if you changed the default location as mention above.
Hard disk image: source image=vmName.vmdk, target path=/VMF/vmName/vmName.vmdk,
If you are happy with everything looks, great then run the command again without the –dry-run. If you need to make changes add the proper switches to the import command after your .ova or .ovf file.
Now we need to unregister the vm for the converting to do that issue this command.
$ VBoxManage unregistervm /VMF/vmName/vmName.vbox