avoid select pages wagtail

models.py

from django.db import models

from wagtail.core.models import Page
from wagtail.core.fields import RichTextField
from wagtail.admin.edit_handlers import FieldPanel
from wagtail.search import index
from wagtail.images.edit_handlers import ImageChooserPanel


class TallerIndexPage(Page):
    template = "talleres/talleres_page.html"

    intro = RichTextField(blank=True)

    content_panels = Page.content_panels + [
        FieldPanel('intro', classname="full")
    ]


class Taller(Page):
    template = "talleres/taller_single_page.html"

    fecha_inicio_taller = models.DateField("Fecha Inicio Taller", null=True, blank=True)

    lugar_taller = models.CharField(max_length=150, null=True, blank=True, verbose_name="Lugar donde se realizará el Taller")

    descripcion = RichTextField(blank=False, null = False, verbose_name="Descripción del Taller")
    
    contenido = RichTextField(blank=True, null = True, verbose_name="Todo el contenido extra del taller",  default="<p>some HTML here</p>")

    imagen_taller = models.ForeignKey(
        "wagtailimages.Image",
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="+",
    )

    search_fields = Page.search_fields + [
        index.SearchField(
            'descripcion'),
    ]

    content_panels = Page.content_panels + [


        FieldPanel('fecha_inicio_taller'),
        FieldPanel('lugar_taller'),
        FieldPanel('descripcion'),
        FieldPanel('contenido'),

        ImageChooserPanel('imagen_taller'),
    ]

    class Meta:
        verbose_name = 'Taller'
        verbose_name_plural = 'Talleres'

wagtail_hooks.py

from wagtail.contrib.modeladmin.options import (
    ModelAdmin, modeladmin_register)
from .models import Taller


class TallerAdmin(ModelAdmin):
    model = Taller
    menu_label = 'Talleres'  # ditch this to use verbose_name_plural from model
    menu_icon = 'pilcrow'  # change as required
    menu_order = 200  # will put in 3rd place (000 being 1st, 100 2nd)
    add_to_settings_menu = False  # or True to add your model to the Settings sub-menu
    # or True to exclude pages of this type from Wagtail's explorer view
    exclude_from_explorer = False
    list_display = ('title', 'first_published_at', 'fecha_inicio_taller' )
    list_filter = ('first_published_at', 'fecha_inicio_taller')
    search_fields = ('title', 'fecha_inicio_taller')


# Now you just need to register your customised ModelAdmin class with Wagtail
modeladmin_register(TallerAdmin)