One Click Demo Import Change the Plugin Page Markup

plugin-page.php

<?php

add_action( 'init', function() {
	remove_filters_with_method_name( 'admin_menu', 'create_plugin_page', 10 );
	remove_filters_with_method_name( 'admin_enqueue_scripts', 'admin_enqueue_scripts', 10 );
}, 99 );

function remove_filters_with_method_name( $hook_name = '', $method_name = '', $priority = 0 ) {
    global $wp_filter;
    // Take only filters on right hook name and priority
    if ( ! isset( $wp_filter[ $hook_name ][ $priority ] ) || ! is_array( $wp_filter[ $hook_name ][ $priority ] ) ) {
        return false;
    }

    // Loop on filters registered
    foreach ( (array) $wp_filter[ $hook_name ][ $priority ] as $unique_id => $filter_array ) {
        // Test if filter is an array ! (always for class/method)
        if ( isset( $filter_array['function'] ) && is_array( $filter_array['function'] ) ) {
            // Test if object is a class and method is equal to param !
            if ( is_object( $filter_array['function'][0] ) && get_class( $filter_array['function'][0] ) && $filter_array['function'][1] == $method_name ) {
                // Test for WordPress >= 4.7 WP_Hook class (https://make.wordpress.org/core/2016/09/08/wp_hook-next-generation-actions-and-filters/)
                if ( is_a( $wp_filter[ $hook_name ], 'WP_Hook' ) ) {
                    unset( $wp_filter[ $hook_name ]->callbacks[ $priority ][ $unique_id ] );
                } else {
                    unset( $wp_filter[ $hook_name ][ $priority ][ $unique_id ] );
                }
            }
        }
    }
    return false;
}

add_action( 'admin_menu', function() {

	$plugin_page_setup = array(
		'parent_slug' => 'themes.php',
		'page_title'  => esc_html__( 'One Click Demo Import' , 'pt-ocdi' ),
		'menu_title'  => esc_html__( 'Import Demo Data' , 'pt-ocdi' ),
		'capability'  => 'import',
		'menu_slug'   => 'pt-one-click-demo-import',
	);

	$plugin_page = add_submenu_page(
		$plugin_page_setup['parent_slug'],
		$plugin_page_setup['page_title'],
		$plugin_page_setup['menu_title'],
		$plugin_page_setup['capability'],
		$plugin_page_setup['menu_slug'],
		apply_filters( 'pt-ocdi/plugin_page_display_callback_function', 'display_plugin_page' )
	);

	register_importer( $plugin_page_setup['menu_slug'], $plugin_page_setup['page_title'], $plugin_page_setup['menu_title'], apply_filters( 'pt-ocdi/plugin_page_display_callback_function', 'display_plugin_page' ) );
} );

function display_plugin_page() {
	require_once get_template_directory() . '/template-parts/import.php';
}

add_action( 'admin_enqueue_scripts', function() {

	$import_files = \OCDI\Helpers::validate_import_file_info( apply_filters( 'pt-ocdi/import_files', array() ) );

	wp_enqueue_script( 'jquery-ui-dialog' );
	wp_enqueue_style( 'wp-jquery-ui-dialog' );

	wp_enqueue_script( 'ocdi-main-js', PT_OCDI_URL . 'assets/js/main.js' , array( 'jquery', 'jquery-ui-dialog' ), PT_OCDI_VERSION );

	// Get theme data.
	$theme = wp_get_theme();

	wp_localize_script( 'ocdi-main-js', 'ocdi',
		array(
			'ajax_url'         => admin_url( 'admin-ajax.php' ),
			'ajax_nonce'       => wp_create_nonce( 'ocdi-ajax-verification' ),
			'import_files'     => $import_files,
			'wp_customize_on'  => apply_filters( 'pt-ocdi/enable_wp_customize_save_hooks', false ),
			'import_popup'     => apply_filters( 'pt-ocdi/enable_grid_layout_import_popup_confirmation', true ),
			'theme_screenshot' => $theme->get_screenshot(),
			'texts'            => array(
				'missing_preview_image' => esc_html__( 'No preview image defined for this import.', 'pt-ocdi' ),
				'dialog_title'          => esc_html__( 'Are you sure?', 'pt-ocdi' ),
				'dialog_no'             => esc_html__( 'Cancel', 'pt-ocdi' ),
				'dialog_yes'            => esc_html__( 'Yes, import!', 'pt-ocdi' ),
				'selected_import_title' => esc_html__( 'Selected demo import:', 'pt-ocdi' ),
			),
			'dialog_options' => apply_filters( 'pt-ocdi/confirmation_dialog_options', array() )
		)
	);

	wp_enqueue_style( 'ocdi-main-css', PT_OCDI_URL . 'assets/css/main.css', array() , PT_OCDI_VERSION );
} );