You can rename or remove your images easily.
View and edit images
To view or edit an image, just click it and a popup will alow you to view metadata like file type and creation date, as well as the title. It is originally derived from the filename on upload, but you can change it here.
To delete images, click the delete images... button. The following dialog allows you to select individual or all images, and subsequently will remove them.
Caution: this action will destroy poster settings using a gallery image. Make sure to change the poster settings for affected media.