How do I cancel/stop Media Upload?

I started an upload of a group of images that I thought I wanted in my post. It wasn’t until after I started the upload that I realized that it was the wrong group of images. To make things worse, the images are very LARGE and taking forever to upload.

I don’t see anything that reads “Cancel Upload” or “Stop upload”?
It’s going to take All Day to upload all those images, how do I cancel it?
Thanks.