I want to change location of main navigation

Hello,

I was looking for a theme that allowed up to 4 columns and had the main navigation in the left sidebar as opposed to the header. This was difficult to find, but I found this theme which seems like one I can work with. The sidebar nav will need to be styled as a main nav to stand out. Does anyone have any suggestions as to how to safely and effectively change the structure to remove the header navigation completely and place it in a sidebar? It looks like to turn off the main nav in the header from the interface, I would have to get each page id and place it in the text field that removes those pages and just use the pages widget in the side bar (I think). But then, if I remove the pages from the header, will they still appear in the pages sidebar widgets...? Would it be better to go into the Header php and just remove that from the html structure? Some insight would be helpful in how to do this properly, so I don't screw up the theme by attempting this on my own. Thanks for your help!