Hi Budur,
If you look at
/ovirt-engine/api/roles
You'll see a list of roles.
The role which is equivalent to the "VM owner" is UserVmManager, and you can see that its ID is "def00006-0000-0000-0000-def000000006".
Then, if you go to /ovirt-engine/api/users/user-id/permissions you'll get all the permissions granted to this user, and there you can look for this permission.
Whenever it exists, with combination of a VM, it will mean that this user is the UserVmManager of this VM.
It doesn't mean he created it, but that he was granted this permission.
Hope that is what you were looking for.
Regards,
Oved