How do I remove a directory that is not empty?

From http://php.net/manual/en/function.rmdir.php#91797

Glob function doesn't return the hidden files, therefore scandir can be more useful, when trying to delete recursively a tree.

<?php 
public static function delTree($dir) { 
   $files = array_diff(scandir($dir), array('.','..')); 
    foreach ($files as $file) { 
      (is_dir("$dir/$file")) ? delTree("$dir/$file") : unlink("$dir/$file"); 
    } 
    return rmdir($dir); 
  } 
?>

There are plenty of solutions already, still another possibility with less code using PHP arrow function:

function rrmdir(string $directory): bool
{
    array_map(fn (string $file) => is_dir($file) ? rrmdir($file) : unlink($file), glob($directory . '/' . '*'));

    return rmdir($directory);
}

I didn't arrive to delete a folder because PHP said me it was not empty. But it was. The function by Naman was the good solution to complete mine. So this is what I use :

function emptyDir($dir) {
    if (is_dir($dir)) {
        $scn = scandir($dir);
        foreach ($scn as $files) {
            if ($files !== '.') {
                if ($files !== '..') {
                    if (!is_dir($dir . '/' . $files)) {
                        unlink($dir . '/' . $files);
                    } else {
                        emptyDir($dir . '/' . $files);
                        rmdir($dir . '/' . $files);
                    }
                }
            }
        }
    }
}

function deleteDir($dir) {

    foreach(glob($dir . '/' . '*') as $file) {
        if(is_dir($file)){


            deleteDir($file);
        } else {

          unlink($file);
        }
    }
    emptyDir($dir);
    rmdir($dir);
}

So, to delete a directory and recursively its content :

deleteDir($dir);

function delTree($dir) { 
    $files = array_diff(scandir($dir), array('.','..')); 
     foreach ($files as $file) 
       (is_dir("$dir/$file")) ? delTree("$dir/$file") : @unlink("$dir/$file"); 
     return @rmdir($dir); 
}