<?php
function iterateDirectory($i)
{
    echo '<ul>';
    foreach ($i as $path) {
        if ($path->isDir())
        {
            echo '<li>';
            iterateDirectory($path);
            echo '</li>';
        }
        else
        {
            echo '<li>'.$path.'';
            echo "<form action='delete.php' method='POST'>";
            echo "<button type='submit' class='btn btn-secondary'>Delete image</button>";
            echo "</form>";
            echo "</li>";
        }
    }
    echo '</ul>';
}

$iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($curuser));

iterateDirectory($iterator);