It seems that if you want to delete one or more tables in a DELETE query containing a JOIN, you will need to specify the table(s) to delete between DELETE and FROM.
Joomla's delete() method does not provide the necessary output - as you have discovered.
If you wish to patch the output from the query methods, ...
A MySQL DELETE query doesn't have a column value between keywords DELETE and FROM.
There is also no benefit to declaring a table alias.
owner is a mysql keyword, but not a RESERVED keyword, so it doesn't need to be backtick-wrapped.
$db = Factory::getDBO();
$query = $db->getQuery(true)