Wordpress multi level menu

I have designed a WP website, and I have put the navigation in a widget area on the left side. That's all good.

The navigation shows all 1st. level and sub level menu. That's all good too.

The problem is, when I click/activate a 1st. level menu. All the sub level menus for that 1st. level are automaticaly highlighted. Any ideas to how to remove the submenu highlight, when I click the parent 1st. level menu?

The website is build with Headway.

See the website here: http://ift.tt/16t04j4