Exclude categories from categories widget in WordPress

exclude_categories.php

// Add to functions.php in the theme to exclude categories from the built-in categories widget
function exclude_widget_categories($args){
$exclude = "105,102,108,112"; // The IDs of the excluding categories
$args["exclude"] = $exclude;
return $args;
}
add_filter("widget_categories_args","exclude_widget_categories");