peopleinside I checked better, and you actually can't do that.
To delete an image uploaded anonymously (this is how images are uploaded right now with this extension), you need the
deletehash, which is a string that Imgur gives to each image and that you can then use to delete the image it belongs to. This value is currently not stored by the extension, so the
deletehash is lost as soon as the image is uploaded. That value is required to delete public anonymous images.
Uploading images not anonymously so that they are saved to your account would be possible, but that would complicate things a lot...
So for now I can't actually thing of an easy way to manage uploaded images, sorry.