Deleting variables at the end of the method decreases spent memory?

Question

In php we have the method unset to erase variables from memory, I have a doubt about that.

After a method is executed, are its local variables automatically deleted from memory? Or is it good practice to use the unset to erase them and release a little?

Follow an example:

private function getAllFiles()
{
    $files = (new FinderFiles)->getFiles();

    $progress = ProgressHelper::start($this->output, 'files', count($files));
    $repository = ClassesRepository::instance();

    foreach ($files as $file) {
        $repository->pushClass(new AnalyzedClass($file->getRealPath()));
        $progress->advance();
    }
    $progress->finish();
    unset($files, $progress, $repository);
}

With the line unset($files, $progress, $repository); program would consume less memory or the exclusion of these variables is already made?