The border around the images/logos at the bottom of the page? That’s coming from the settings from when you insert an image into a post/page. The css it’s coming from is below. You can use the below css to remove it if you can’t adjust it from inside the image settings.

.post-content .alignnone, .post-content .alignleft, .post-content .alignright, .post-content .aligncenter {
background: none
border-color: none
border-style: none;
border-width: 0;
box-shadow: none;