JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="board-box__attachments">
  
  <li>
    <div class="th">files</div>
    <div class="td">
      <input type="file">
      <button class="btn btn-plus"> + </button>
    </div>
  </li>
  

</ul>

CSS

li {
  width : 50%;
  background : lightblue;
  list-style : none;
  padding : 1em;
  border-bottom : 1px solid white;
}

.th { 
  width : 100px;
  float: left;
}

.td {
  width: 100%;
}

JavaScript

$(".btn-plus").click(function(){
    $('.board-box__attachments').prepend('<li><div class="th">files</div><div class="td"><input type="file"><button class="btn btn-minus"> - </button></div></li>');
    return false;
})


$(".btn-minus").click(function(){
	  $(this).nextUntil('li').remove()
})