Add or remove links to the navigation bar depending on screen size in 5.7

Step 1 Edit the autonav block. In the view.php (Make sure you choose the correct view.php. If you are using a template like the responsive_header_navigation you will have to edit the view.php in that folder) you need to enable the $navItem->attrClass attribute. Line 88 you need to un comment the following

/*
if (!empty($ni->attrClass)) {
    //class that can be set by end-user via the 'nav_item_class' custom page attribute
    $classes[] = $ni->attrClass;
}
*/

to

if (!empty($ni->attrClass)) {
    //class that can be set by end-user via the 'nav_item_class' custom page attribute
    $classes[] = $ni->attrClass;
}

Step 2 Create a Page attribute. In the dashboard Pages & themes, Attributes and create a Text Attribute called nav_item_class. This is documented in the view.php file.

Then for the page depending on what screen size you want to hide or show the link you can use some bootstrap css.

Example if you want to add a facebook and twitter link to a responsive mobile menu you would add them as external links within the sitemap. Then in the dashboard go Sitemap, Page Search and choose attributes for the relevant link. Add the nav_item_class to the page and enter visible-xs

More Bootstrap Available classes are available at http://getbootstrap.com/css/#responsive-utilities-classes