This is the 'Bare Bones' template for PivotX. It's not much to look at, but it's a good start to write your own templates. It contains most of the usual tags you'd like to have in a template, with a minimum of CSS/HTML.
You can change this text by editing the file '_sub_about.tpl' in your pivotx/templates/bare_bones/ folder. You can do this by directly editing the file, or you can go to 'Manage Media' » 'Templates' in the PivotX interface.
This is the footer.