You should be able to open your image (that is, enlarge it) then use the "Manage the tags on this image" at the bottom of the page. I think you can delete the tag then add a new one if you know the correct name or you can delete the entire image.
Name: Suzanne/Sue Sebastopol, CA (Zone 9a) Sunset Zone 15
I just tested on one of mine and I was able to delete it. But it may be a different setting for me as an admin.
I do believe you should be able to do it too Evan. You have to double click on the tag. Try that too Paul.