How can PHP be used to recursively delete files within a directory?

To recursively delete files within a directory using PHP, we can use a combination of `scandir()` to get a list of files and directories within the target directory, and `unlink()` to delete files. We also need to check if each item is a file or a directory, and if it's a directory, recursively call the function to delete files within that directory.

function deleteFiles($dir){
    $files = array_diff(scandir($dir), array('.','..'));
    foreach($files as $file){
        $path = $dir.'/'.$file;
        if(is_dir($path)){
            deleteFiles($path);
        }else{
            unlink($path);
        }
    }
    rmdir($dir);
}

// Usage
$directory = 'path/to/directory';
deleteFiles($directory);