This is a mod I have done in the past.
There are a few issues you need to consider. The skin has set the low title bar there to allow space for RSS feeds, and submenu (and glow bars if you use them). If you never use RSS feeds (I do not) then absolutely you can change this.
You need to edit includes_home.xml. Around line 231 there is an animation slide. Experiment by increasing the slide until you get the look you want.
This will also impact on on the HorizontalMenuSystemBar slides (around lines 93-100). You will need to change some of them once you have the main menu in the right place.
Whilst experimenting I suggest you ensure that in skin settings you have the submenu always visible and glow bars on - just makes it easier to ensure that everything is displayed correctly