delete
from products
where id in (SELECT *
FROM products
GROUP BY part_number
 HAVING count(*) > 1 and manufacturer_id="4146"
)

delete
from products
where id IN (SELECT id
FROM products
WHERE manufacturer_id="4146"
GROUP BY part_number
 HAVING count(*) > 1
)

delete
from products
where id IN
(SELECT t.id FROM (
(SELECT id
FROM products
WHERE manufacturer_id="4146"
GROUP BY part_number
 HAVING count(*) > 1 ) t
)