Are the images stored in variables? Written to files? Hanging on the wall in the Louvre? Since "10000" cannot be a variable name and is not listed in the catalogue of images in the Louvre, I'm guessing these are file names, like "10000.jpg". You want to rename the files?
You can use movefile() to create a copy of the file with a new name. Then you can use delete() to delete the old copies forever (but you already made a backup of the original files before you did any of this).
