I would like to remove all span tags from the editor text.  I added this to the bottom of the aspx page:

 
<script type="text/javascript" language="javascript">
function CuteEditor_FilterHTML(editor,code)
{
return code.replace(/(<span[^\>]*\>)([\s\S]*)(\<\/span\>)/i, "$2");
}
function CuteEditor_FilterCode(editor,code)
{
return code.replace(/(<span[^\>]*\>)([\s\S]*)(\<\/span\>)/i, "$2");
}
</script>

 

 I entered this text in HTML mode:
<span>a</span><span>b</span>

 

After switching to Normal and back to HTML it shows:

a</span>b