Hi eric.
Been there, done that. In my opinion that's a big product flaw. The only way to "steal it" is asking to the user to export it's content. Otherwise, a non so nice resolution would be to remove the user temporarily so the content become orphaned. You own it, remove it and then you can enable the user again.
Sorry for that "workaround" but that worked for me.
Hope vROps product owners find a way in newer versions.
Regards