It's not possible to un license an image but I've added 2 image credits to your account so you can select another images to use instead.
Hope this helps !!!
I did the same thing. I wish there was a confirm license button, because I clicked an image to preview it and nothing happened then clicked again and then hover menu appeared and I accidentally clicked the Save to Computer. While it was "working" I exited the tab but it still went through:
Want to un-license both of these.
You have to open a ticket like I did so they can credit your account.