title: Delete the last instance of a letter in string
body: <p>How do I delete only the last <code>"l"</code> from a string and not the others?</p>
  
  <pre><code>string = "Hello"
  </code></pre>
  
  <p>desired outcome:</p>
  
  <pre><code>string # =&gt; "Helo"
  </code></pre>
  
  <p>I did:</p>
  
  <pre><code>string.delete!("l")
  string #= &gt; "Heo"
  </code></pre>