This might help someone else who comes across this thread - to change a particular menu to revert to the default WP walker (maybe the easiest way to remove Bootstrap dropdown data attributes and just list links inline) see following code (the last argument to the wp_nav_menu function sets the walker to the default):
<?php
if (has_nav_menu('start_here')) :
wp_nav_menu(array('theme_location' => 'start_here', 'menu_class' => 'list-inline', 'walker' => new Walker_Nav_Menu));
endif;
?>