Child elements cannot be cascaded when the parent element is deleted

Question

When trying to delete an element from the table that is the element to which other elements of the same table are linked, an error occurs: java.sql.SQLIntegrityConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails (company.product, CONSTRAINT FKq39fk2qbnqmgxuiqh5wrccgy8 FOREIGN KEY (product) REFERENCES product (id))

My entity includes an object of the same class. Here is her code:

@Entity
@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class Product {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column (name = "name")
    private String name;

    @Column (name = "cipher")
    private String cipher;

    @Column (name = "route")
    private String route;

    @Enumerated (value = EnumType.STRING)
    @Column (name = "type")
    private Type type;

    @JoinColumn (name = "product")
    @ManyToOne
    private Product mainProduct;

    public enum Type{
        DETAIL ("Деталь"),
        ASSEMBLY ("Сборочная единица"),
        PURCHASED ("Покупная"),
        MATERIAL ("Материал"),
        NORMALIZED ("Стандарное изделие"),
        ASSEMBLY_NORMAL ("Сборочная нормаль");

        private String type;

        Type(String type){
            this.type = type;
        }

        public String getType(){
            return type;
        }
    }
}

Why can't I delete the parent element by deleting the child elements along with it?