How to change file image file name?

I have a website project in js. There are some images (jpge files). I need to rename the files with a more appropriate name to improve seo. The project was being handled by other person before, so i do not have any idea how to change the image name.

I though i would be just easy as , just change the name, but there is no rename option. Also i tried to upload new image with different name but new image also gets the last name as per file.