Delete entire key

I’m trying to delete part of a record. Say I have this record:

{
    "objectID": "1234",
    "location_city": "Albuquerque",
    "location_country": "USA"
}

Is there a way to delete the “location_city” attribute completely without performing a full update of the record? I’d expect something like this in PHP, but I can’t seem to find a way in the API documentation. I appreciate your help!

$index->partialUpdateObject([
   'objectID' => '1234',
   'location_city' => [
       '_operation' => 'RemoveKey',
   ],
]);