Can’t unregister parent theme’s CPT from my child theme

you cannot remove a hook when you are in the same hook with the same priority.

a solution is to hook the action with a lower priority

add_action('init', 'remove_cpt', 5);

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)