To change the name of a file, use File.rename like so:
File.rename("file1.txt", "file2.txt")
You can delete either one file at a time or many at once:
File.delete("file1.txt") File.delete("file2.txt", "file3.txt", "file4.txt") File.unlink("file1.txt")
File.unlink does exactly the same thing as File.delete.