Change catergory image

I know this is probably a very obvoius answer, but having looking in the help I still don't get it.
I want to change the catergory images to my own, but there is no delete button to remove the exisiting one, and although I can select the one I wish to upload there is no option to uploaded it?
Any ideas?
Thanks

Once you selected it, you can just save the category and your image will be uploaded and will replace your old one.

Brilliant, thanks for that. So easy when you know how.