I'm sorry but WordPress.com requires that you keep the footer credits visible and clickable. It is part of the terms of service and even WordPress.com VIPs like Time and CNN have a footer credit present.
That said, I think the reason Google picked up the footer text on your blog is because that's probably the only text you had on the page when Google happened to crawl your site. If you add some other text on your home page, in addition to your images, Google should eventually pick up that text instead. How long it takes to pick up a change though, is up to Google and not up to WordPress.com.
There is a way to connect your site to Google and get some diagnostics. See this help page for details if you want to try it out: