Hi Michaela-
I took a look at your site, and it looks like the site is using a custom-designed theme, not a BoldGrid theme, so I can’t say for sure.
If the theme is designed using WordPress standards and best-practice, that section of your header would be in a Widget, but as far as I can tell it might not be for your site.
It’s possible that the your predecessor might have hard-coded that information into the theme code itself. If that’s the case, you’ll want to make sure you get a full backup of the website before attempting to update it, because a mistake could crash the entire site.
You can use your Appearance > Theme Editor and look for a file like header.php to see if you can locate the code.