Syntax Error in Mysql Delete Trigger with conditions

I have written a small trigger function in MySQL . This is the trigger query i have written and give syntax error in code.

Error : You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'cp WHERE cp.customer_plan_id= first_id;

DELIMITER $$ CREATE TRIGGER delete_plan_on_delete_customer AFTER DELETE ON customers FOR EACH ROW BEGIN DECLARE active_plan INT; DECLARE first_id INT;

SET active_plan = (SELECT is_active
FROM customer_plans 
WHERE customer_id=OLD.customer_id AND first_plan_id=1);

if(active_plan = 0)THEN

    SET first_id = (SELECT customer_plan_id
    FROM customer_plans 
    WHERE customer_id=OLD.customer_id AND first_plan_id=1);

    DELETE customer_plans cp WHERE `cp`.`customer_plan_id`= first_id;

END IF; END$$ DELIMITER ;