As of now, there is no on/off option but I will surely add this and in the next update.
You can still do this though manually by dragging the welcome bar box to the GRAY sidebar drop-down menu area within your ‘Skin Editor’.
This will keep all of your options saved and simply remove the welcome bar from your page. You can do this whenever you don’t have breaking news.
When you want it to display again, you will find it within the drop-down list on your ‘Skin Editor’ page, simply add it where it was before and you will have all the previous settings restored.
*Be sure you don’t drag it to the PINK area or you will erase your settings*
Hope this helps.