Remove changeable template options from Page editor

removeTemplateOptions.php

<?php

wire()->addHookAfter('ProcessPageEdit::buildFormSettings', function (HookEvent $e) {
    $page = $e->object->getPage();
    if ($page->template != "basic") return;

    /** @var $templatesField InputfieldSelect */
    $templatesField = $e->return->children->get('id=template');
    $templates = $templatesField->getOptions();

    // sort first
    asort($templates);
    foreach ($templates as $tid => $tname) {
        // remove incompatible fields
        $template = $e->templates->get($tid);
        if (!$template) continue;
        if (strpos($template->tags, 'allow') === false) unset($templates[$tid]);
    }
    $templatesField->set('options', $templates);
});