DELETE FROM courses WHERE id_course = 'course24';
DELETE FROM courses WHERE id_course = 'course39';
DELETE FROM courses WHERE id_course = 'course115';
DELETE FROM courses WHERE id_course = 'course159';
DELETE FROM courses WHERE id_course = 'course124';
DELETE FROM courses WHERE id_course = 'course129';
DELETE FROM courses WHERE id_course = 'course23';
DELETE FROM courses WHERE id_course = 'course8';
DELETE FROM courses WHERE id_course = 'course104';
DELETE FROM courses WHERE id_course = 'course126';
DELETE FROM courses WHERE id_course = 'course91';
