JSFiddle - React, Tailwind, and code Playground

HTML

<div class="elfile_1 fcot">lorem ipsum <button type="button" class="btn btn-default btn-sm" onclick="delete_file(1)"><i class="fa fa-times" aria-hidden="true">a</i></button></div>
<div class="elfile_2 fcot">lorem ipsum <button type="button" class="btn btn-default btn-sm" onclick="delete_file(2)"><i class="fa fa-times" aria-hidden="true">b</i></button></div>
<div class="elfile_3 fcot">lorem ipsum <button type="button" class="btn btn-default btn-sm" onclick="delete_file(3)"><i class="fa fa-times" aria-hidden="true">c</i></button></div>

JavaScript

function delete_file(idx){
  $('.elfile_'+idx).remove();
  var inputs = $(".fcot");

  //for(var i = 0; i < inputs.length; i++){ 
    $(".fcot").each(function(i,v){              
       $(this).attr('class',$(this).attr('class').replace(/\belfile.*?\b/g, ''));
       $(this).addClass('elfile_'+ (i + 1));

       $(this).find('button').each(function() {
           $(this).attr('onclick', 'delete_file('+ (i + 1) +')');
       });
    });
  //}
}