Undeletable Image

I would be grateful for your help, if possible.

Here’s my WordPress site link: http://www.elizabethhuergo.com

There is a box that appears on the upper right-hand side of the fixed page.

Sometimes it appears to be empty–with a tiny logo inside. Other times, the WordPress 2012 image appears.

The browser you use to view the page seems to make a difference: Windows Explorer? No box appears at all.
Google Chrome and Firefox? The unwanted image appears.

I’ve tried to upload, save and delete.

I’ve also tried to locate and delete the code.

The edit never takes.

If you have any suggestions, I would appreciate hearing from you. Thank you so much! Liz