So far, you've got three completely different answers. Let's figure out what it is you're trying to do.

The file you attached has no blank lines, and its last line ends with a newline, as is customary with a Unix text file, of which CSVs are a specific kind.

I assume you don't want to delete blank lines, as your sample contains none. If you do, that's what the command you stated will do, almost. It'll actually delete every line that contains only a single character.

Mataglap's answers will convert DOS/Windows text files to Unix text files and the other way around. (Although the nearly ubiquitous dos2unix and unix2dos commands will do the same thing.) That doesn't seem to match your description, though.

If you want to delete the final newline from a text file, what I suggested will work, although there are other ways, few of them one-liners, since Unix command line utilities are designed to work with text files and what you want to do would make it a non-standard text file.

On the other hand, maybe you're confused about the trailing newline and you think it's not supposed to be there. It is. Are you having a problem with the CSV file that makes it look like you have an extra blank line?