title: Remove characters by position from string
body: <p>I want to remove two characters by position from string, form example I want to remove character from <code>subCadenaTX4</code> at position 4 and 5</p>
  <pre><code>let fechaNacRFC = &quot;25/12/1997&quot;
  let subCadenaTX4 = fechaNacRFC!.replacingOccurrences(of: &quot;/&quot;, with: &quot;&quot;, options: NSString.CompareOptions.literal, range: nil)
  print(subCadenaTX4) // It will be 25121997
  </code></pre>
  <p>I read that I can use <code>removeAtIndex</code> but what it is the way in this case?</p>
  <p>My expected output: <code>251297</code></p>