Create directory

  if (!is_dir('temp/'))
    mkdir('temp', 0755, true);

define("MY_FILE_DOWNLOADS_DIRECTORY",                      "file-download/");

  if (!is_dir($_SERVER['DOCUMENT_ROOT'] . "/" . MY_FILE_DOWNLOADS_DIRECTORY))
  {
    mkdir($_SERVER['DOCUMENT_ROOT'] . "/" . MY_FILE_DOWNLOADS_DIRECTORY, 0777, true);
  }

Delete directory and its contents

//*******************************************************
//*******************************************************
//********** DELETE DIRECTORY AND ITS CONTENTS **********
//*******************************************************
//*******************************************************
function DeleteDirectoryAndContent ($DirectoryPath)
{
  if (is_dir($DirectoryPath))
  {
    $Files = scandir($DirectoryPath);
    foreach ($Files as $File)
    {
      if ($File !== '.' && $File !== '..')
      {
        $FilePath = $DirectoryPath . '/' . $File;
        if (is_dir($FilePath))
          DeleteDirectoryAndContent($FilePath);
        else
          unlink($FilePath);
      }
    }
    rmdir($DirectoryPath);
  }
}

Delete directory contents only

//****************************************************
//****************************************************
//********** DELETE DIRECTORY CONTENTS ONLY **********
//****************************************************
//****************************************************
function DeleteDirectoryContentOnly ($DirectoryPath)
{
  if (is_dir($DirectoryPath))
  {
    $Files = scandir($DirectoryPath);
    foreach ($Files as $File)
    {
      if ($File !== '.' && $File !== '..')
      {
        $FilePath = $DirectoryPath . '/' . $File;
        if (is_dir($FilePath))
          DeleteDirectoryAndContent($FilePath);
        else
          unlink($FilePath);
      }
    }
  }
}

Delete old directory contents

//*****************************************************************
//*****************************************************************
//********** DELETE DIRECTORY CONTENTS OLDER THAN # MINS **********
//*****************************************************************
//*****************************************************************
function DeleteOldDirectoryContent($DirectoryPath, $DeleteOlderThanMins)
{
  if (!is_dir($DirectoryPath))
    return;

  $Files = scandir($DirectoryPath);
  $TimeNow = time();
  $MaxAgeSecs = $DeleteOlderThanMins * 60;      //Seconds

  foreach ($Files as $File)
  {
    if ($File==="." || $File==="..")
      continue;

    $FilePath=$DirectoryPath.DIRECTORY_SEPARATOR.$File;
    if (is_file($FilePath))
    {
      $FileMTime = filemtime($FilePath);
      if ($FileMTime !== False && ($TimeNow - $FileMTime) > $MaxAgeSecs)
      {
        //echo "$FilePath<br>";
        unlink($FilePath);
      }
    }
  }
}