You should use a HTML parser instead. I like htmlCleaner, because it gives me a pretty printed version of the HTML.
With htmlCleaner you can do:
TagNode root = htmlCleaner.clean( stream );
Object[] found = root.evaluateXPath( "//div[id='something']" );
if( found.length > 0 && found instanceof TagNode ) {
((TagNode)found[0]).removeFromTree();
}