Cant remove border? Keeps coming back?

I’d guess that the theme has CSS to apply borders to images, but without seeing your site, no way to know or help more.

The borders are from here:

#masthead img, #featured-content img, #recent-content img, .entry-content img, .entry-thumb img, .comment-content img, .widget img {
    background: none repeat scroll 0 0 #FFFFFF;
    border: 1px solid #BBBBBB;
    max-width: 99.35%;
    padding: 1px;
}

But to change just that image, try adding this to your custom CSS – make sure that you are not modifying theme files or your changes will be lost when the theme is updated –

#masthead img {
    border: 0;
}

That’s way too much code to post here – http://codex.wordpress.org/Forum_Welcome#Posting_Code – and CSS is all visible on your site.

BTW, I don’t see a border on that page/image.