Admin Dashboard Access

function restrict_dashboard_access() {

    // Allow AJAX requests to proceed

    if ( defined( 'DOING_AJAX' ) && DOING_AJAX ) {

        return;

    }

    // Check if user is not an administrator

    if ( ! current_user_can( 'administrator' ) && is_admin() ) {

        wp_redirect( home_url() );

        exit;

    }

}

add_action( 'init', 'restrict_dashboard_access' );