rector/rules/PSR4/NodeManipulator/NamespaceManipulator.php

<?php
declare(strict_types=1);

namespace Rector\PSR4\NodeManipulator;

use PhpParser\Node\Stmt\ClassLike;
use PhpParser\Node\Stmt\Namespace_;

final class NamespaceManipulator
{
    public function removeClassLikes(Namespace_ $namespace): Namespace_
    {
        foreach ($namespace->stmts as $key => $namespaceStatement) {
            if (! $namespaceStatement instanceof ClassLike) {
                continue;
            }

            unset($namespace->stmts[$key]);
        }

        return $namespace;
    }
}