ORA-02292: integrity constraint violated – child record found while creating procedures in ORACLE SQL Developer?

I have written a procedure that has as input the CUSTOMER_ID. Then the procedure deletes the corresponding customer from the table CUSTOMERS.

CREATE OR REPlACE PROCEDURE DELETE_CUSTOMER 
(CUSTOMER_ID NUMBER) AS 
TOT_CUSTOMERS NUMBER;
BEGIN
    DELETE FROM CUSTOMERS
    WHERE CUSTOMERS.CUSTOMER_ID = DELETE_CUSTOMER.CUSTOMER_ID;
    TOT_CUSTOMERS := TOT_CUSTOMERS - 1;
    END;
/

I have to execute the procedure to delete customer with id 1.

EXECUTE DELETE_CUSTOMER(01);

When I do this, I get an error

Error starting at line : 120 in command -
BEGIN DELETE_CUSTOMER(01); END;
Error report -
ORA-02292: integrity constraint (TUG81959.ORDERS_FK_CUSTOMERS) violated - child record found
ORA-06512: at "TUG81959.DELETE_CUSTOMER", line 5
ORA-06512: at line 1
02292. 00000 - "integrity constraint (%s.%s) violated - child record found"
*Cause:    attempted to delete a parent key value that had a foreign
           dependency.
*Action:   delete dependencies first then parent or disable constraint.

I know this is because there is a foreign key for CUSTOMER_ID on the table ORDERS, which means the customer cannot be deleted because he has placed an order.
How do I write the code so that I can first delete the corresponding ORDER_DETAILS and then delete the corresponding ORDERS so that I can finally be able to delete a record from CUSTOMERS?

I tried rewriting the code but I am just lost now:

CREATE OR REPlACE PROCEDURE DELETE_CUSTOMER 
(CUSTOMER_ID_IN NUMBER) AS 
TOT_CUSTOMERS NUMBER;
CURSOR C1 IS
DELETE FROM ORDERS
WHERE ORDERS.ORDER_ID = CUSTOMER_ID.ORDER_ID;
CURSOR C2 IS
DELETE FROM ORDER_DETAILS
WHERE ORDER_DETAILS.ORDER_ID = CUSTOMER_ID.ORDER_ID;
CURSOR C3 IS
DELETE FROM CUSTOMERS
WHERE CUSTOMERS.CUSTOMER_ID = DELETE_CUSTOMER.CUSTOMER_ID;
BEGIN
    OPEN C1;
    OPEN C2;
    OPEN C3;
    IF C1%FOUND AND C2%FOUND AND C3%FOUND
    THEN TOT_CUSTOMERS := TOT_CUSTOMERS - 1;
    END IF;
    CLOSE C1;
    CLOSE C2;
    CLOSE C3;
END;
/

Here are the tables for reference:

No code needed for this, just define the constraint with ON DELETE CASCADE option.

alter table orders drop constraint ORDERS_FK_CUSTOMERS;
alter table orders add constraint ORDERS_FK_CUSTOMERS 
  foreign key (customer_id) references customers(customer_id) on delete cascade;

Same for order_details.