we want to rename our uploaded files after a Upload to the Prismic-CDN. Is there any option to rename the Files/Images? or do we need to download the hole Media back, rename it, upload it again and set it to the right slice?
This isn't possible at the moment but is at the moment, so the only way to do this is manually removing and reuploading as you suggested. We are tracking this as a feature request here though.