DELETE FROM courses WHERE id_course = 'course170';
DELETE FROM courses WHERE id_course = 'course52';
DELETE FROM courses WHERE id_course = 'course82';
DELETE FROM courses WHERE id_course = 'course0';
DELETE FROM courses WHERE id_course = 'course157';
DELETE FROM courses WHERE id_course = 'course93';
DELETE FROM courses WHERE id_course = 'course53';
DELETE FROM courses WHERE id_course = 'course30';
DELETE FROM courses WHERE id_course = 'course74';
DELETE FROM courses WHERE id_course = 'course9';
DELETE FROM courses WHERE id_course = 'course121';
DELETE FROM courses WHERE id_course = 'course40';
DELETE FROM courses WHERE id_course = 'course68';
