Oracle SQL query - select or rows without all ids in other tables
first approach for customers without account 

DELETE FROM CUSTOMER WHERE
ID NOT IN (SELECT CUSTOMER_ID FROM ACCOUNT);


the inner select gives you the list of customer_id's in the accounts table - the remaining data-sets in the customers table can be deleted after your first sentence.

based on that you build a similar select for the case without operations 

DELETE FROM CUSTOMER WHERE
(
  (ID NOT IN (SELECT CUSTOMER_ID FROM OPERATION) ) AND
  (ID NOT IN (SELECT id_account_sender FROM OPERATION) ) AND
  (ID NOT IN (SELECT id_account_receiver FROM OPERATION) )
);


both where conditions can be combined using OR

of course if you first want to run a select to review what is going to be deleted, you can replace "DELETE" with "SELECT *" in the 2 queries I posted