Well its easy to delete certain rows, the below code gets rid of every entry that has owner as 'none' in table prefix_owned_adoptables.
PHP Code:
$mysidia->db->delete("owned_adoptables", "owner = 'none'");
Its also super easy to get the number of rows, simply do:
PHP Code:
$count = $mysidia->db->select("tablename", array(), "conditions")->rowCount();