您必须在删除链接中传递变量.你必须通过 <?php echo $contact['name'];?> 隐藏字段中的名称值或在 URL

You have to pass variable in delete link. You must have to pass <?php echo $contact['name']; ?> name value in hidden field or pass this value in URL

替换

<td class="contact-delete">
      <form action='delete.php' method="post">
      <input type="hidden" name="name" value="">
      <input type="submit" name="submit" value="Delete">
      </form>
</td>

随着

<td class="contact-delete">
    <form action='delete.php?name="<?php echo $contact['name']; ?>"' method="post">
        <input type="hidden" name="name" value="<?php echo $contact['name']; ?>">
        <input type="submit" name="submit" value="Delete">
    </form>
</td>