Remove default category slug from permalink - wordpress

Please write below code in functions.php

// Remove category base
add_action('init', 'no_category_base_permastruct');
function no_category_base_permastruct() {
global $wp_rewrite, $wp_version;
if (version_compare($wp_version, '3.4', '<')) {
$wp_rewrite -> extra_permastructs['category'][0] = '%category%';
} else {
$wp_rewrite -> extra_permastructs['category']['struct'] = '%category%';
}
}

// Add our custom category rewrite rules
add_filter('category_rewrite_rules', 'no_category_base_rewrite_rules');
function no_category_base_rewrite_rules($category_rewrite) {

$category_rewrite = array();
$categories = get_categories(array('hide_empty' => false));
foreach ($categories as $category) {
$category_nicename = $category -> slug;
if ($category -> parent == $category -> cat_ID)// recursive recursion
$category -> parent = 0;
elseif ($category -> parent != 0)
$category_nicename = get_category_parents($category -> parent, false, '/', true) . $category_nicename;

$category_rewrite['(' . $category_nicename . ')/(?:feed/)?(feed|rdf|rss|rss2|atom)/?$'] = 'index.php?category_name=$matches[1]&feed=$matches[2]';
$category_rewrite['(' . $category_nicename . ')/page/?([0-9]{1,})/?$'] = 'index.php?category_name=$matches[1]&paged=$matches[2]';
$category_rewrite['(' . $category_nicename . ')/?$'] = 'index.php?category_name=$matches[1]';
}
// Redirect support from Old Category Base
global $wp_rewrite;
$old_category_base = get_option('category_base') ? get_option('category_base') : 'category';
$old_category_base = trim($old_category_base, '/');
$category_rewrite[$old_category_base . '/(.*)$'] = 'index.php?category_redirect=$matches[1]';

return $category_rewrite;
}