title: Remove style from selected span/text in div
body: <p>Consider this snippet:</p>
  
  <pre><code>&lt;div&gt;
       &lt;span style="color:red;"&gt;a&lt;/span&gt;
       &lt;span style="color:blue;"&gt;a&lt;/span&gt;
       &lt;span style="color:white;"&gt;a&lt;/span&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>How can you remove style from selected by user text?</p>
  
  <p><hr />
  <strong>Edited:</strong> to add clarifications from OP:</p>
  
  <p>Thank you for your answers!
  I had to be more precise. Sorry for that. 
  What do I mean by "selected by user text": selected/highlighted with mouse.
  I have many divs with spans inside(just like it is below-no extra ids,classes for spans:/).</p>
  
  <pre><code>[...]
  &lt;div&gt;
   &lt;span style="color:red;"&gt;a&lt;/span&gt;
   &lt;span style="color:blue;"&gt;b&lt;/span&gt;
   &lt;span style="color:white;"&gt;c&lt;/span&gt;
  &lt;/div&gt;
  &lt;div&gt;
   &lt;span style="color:red;"&gt;d&lt;/span&gt;
   &lt;span style="color:blue;"&gt;a&lt;/span&gt;
   &lt;span style="color:white;"&gt;a&lt;/span&gt;
  &lt;/div&gt;
  [...]
  </code></pre>
  
  <p>What I would like to achieve: user selects with mouse "ab", click button(input type=button) which remove style from selected span/spans. Similar behavior like it is in TinyMCE.</p>