code: public void remove(String chargingStationId, String userIdentity, Class commandClass) {
          EntityManager em = getEntityManager();
  
          EntityTransaction tx = null;
          try {
              CommandAuthorizationId id = new CommandAuthorizationId(chargingStationId, userIdentity, commandClass);
              CommandAuthorization commandAuthorization = em.find(CommandAuthorization.class, id);
  
              if (commandAuthorization != null) {
                  tx = em.getTransaction();
                  tx.begin();
  
                  em.remove(commandAuthorization);
  
                  tx.commit();
              }
          } catch (Exception e) {
              if(tx != null && tx.isActive()) {
                  tx.rollback();
              }
              throw e;
          } finally {
              em.close();
          }
      }
docs: Removes a {@code CommandAuthorization} based on charging station id, user identity and command class if it exists.
  
  @param chargingStationId    charging station identifier.
  @param userIdentity         user identity (user name).
  @param commandClass         command class.