DELETE FROM courses WHERE id_course = 'course24';
DELETE FROM courses WHERE id_course = 'course52';
DELETE FROM courses WHERE id_course = 'course64';
DELETE FROM courses WHERE id_course = 'course108';
DELETE FROM courses WHERE id_course = 'course115';
DELETE FROM courses WHERE id_course = 'course136';
DELETE FROM courses WHERE id_course = 'course138';
DELETE FROM courses WHERE id_course = 'course172';
DELETE FROM courses WHERE id_course = 'course120';
DELETE FROM courses WHERE id_course = 'course4';
DELETE FROM courses WHERE id_course = 'course8';
DELETE FROM courses WHERE id_course = 'course121';
DELETE FROM courses WHERE id_course = 'course137';
DELETE FROM courses WHERE id_course = 'course77';
