Erro ao remover autor.

segque as classes Autor e AutorBean.

@Entity
public class Autor {

    @Id
    @GeneratedValue
    private Integer id;
    private String nome;

    public String getNome() {
        return nome;
    }

    public void setNome(String nome) {
        this.nome = nome;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public void remove(Autor autor) {
        new DAO<Autor>(Autor.class).remove(autor);
    }

}

AutorBean

@ManagedBean
@ViewScoped
public class AutorBean implements Serializable {

    private Autor autor = new Autor();

    public Autor getAutor() {
        return autor;
    }

    /*
     * public void gravar() { System.out.println("Gravando autor " +
     * this.autor.getNome());
     * 
     * this.autor = new Autor();
     * 
     * new DAO<Autor>(Autor.class).adiciona(this.autor); }
     */

    public ForwardView gravar() {
        System.out.println("Gravando autor " + this.autor.getNome());

        if (this.autor.getId() == null) {
            new DAO<Autor>(Autor.class).adiciona(this.autor);
            this.autor = new Autor();
        } else {
            new DAO<Autor>(Autor.class).atualiza(this.autor);
        }

        return new ForwardView("livro");

    }

    public List<Autor> getAutores() {
        return new DAO<Autor>(Autor.class).listaTodos();
    }

    public void carregar(Autor autor) {
        this.autor = autor;
        System.out.println("nome" + autor.getNome());
    }

    public void remover(Autor autor) {
        this.autor.remove(autor);
    }

}

ERROR: Cannot delete or update a parent row: a foreign key constraint fails (`livrariadb`.`livro_autor`, CONSTRAINT `FK9590997AD70C7E4A` FOREIGN KEY (`autores_id`) REFERENCES `autor` (`id`))
mar 20, 2017 4:18:08 PM com.sun.faces.lifecycle.InvokeApplicationPhase execute
ADVERTÊNCIA: #{autorBean.remover(autor)}: javax.persistence.RollbackException: Error while committing the transaction
javax.faces.FacesException: #{autorBean.remover(autor)}: javax.persistence.RollbackException: Error while committing the transaction
    at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:117)
    at javax.faces.component.UICommand.broadcast(UICommand.java:315)
    at javax.faces.component.UIData.broadcast(UIData.java:1092)
    at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:791)
    at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1256)
    at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)