To remove completely or to replace default logo go to Theme Options located under the Appearance section on your left. Click and toggle "Logo Upload" tab where you will see this:



Step One: Go to Appearance > Header > Choose and Upload the logo: http://pix.am/GzPG/



Step Two: Drag all the way across your new logo like this: http://pix.am/At7T/



Step There: Once you dragged to fit please click on "Skip Cropping, Publish Image As Is: http://pix.am/cbFU/



Results on frontpage: http://pix.am/dxMv/



If you don't have a logo, or don't want one at all, click on "Remove Header Image" and you will no longer have any logos and instead plain text will be displayed on all of your pages like this:



And no worries, nothing is "written in stone" or permanent, when and if you change your mind you can always either restore the default logo, or upload your very own as well.