Remove trailing slash

You can use this untrailingslashit($url). It will remove any trailing slashes.

You can remove the trailing slash globally by going to “Settings > Permalinks”, and set your own custom structure without the trailingslash.

For the generated links inside your theme you could try the following – this will remove trailingslashes for links that have been generated by the the_permalink() function for posts and pages.

function permalink_untrailingslashit($link) {
	return untrailingslashit($link);
}
add_filter('page_link', 'permalink_untrailingslashit');
add_filter('post_type_link', 'permalink_untrailingslashit');