I have stumbled upon this problem for one hour. After an hour, I tried debugging and this helped:
$('.list').on('click', 'span', (e) => {
$(e.target).parent().remove();
});
HTML:
<ul class="list">
<li class="task">some text<span>X</span></li>
<li class="task">some text<span>X</span></li>
<li class="task">some text<span>X</span></li>
<li class="task">some text<span>X</span></li>
<li class="task">some text<span>X</span></li>
</ul>