Can't find an image file I need to delete

I’m trying to find an image that’s associated to my domain so that I can delete it. When I click on the direct url/link link to the file, the image displays in a browser. When I try to find the image in my WordPress admin area, it doesn’t show up.

The path is: <domain>/files/<image>.jpg

Where can I find the contents of the /files/ folder in WordPress? How can I locate this file to delete?

Thanks for your help in advance.