See if there's anything else worth fixing in the post.
- Are there any spelling errors?
- Acronyms missing explanation?
- Capitalization issues?
- Could you add a little formatting to make it easier to read?
- Are there links to provide context?
If your answer to all of these questions is "no" (and it rarely is), and the post really needs to be edited, then you could drop by Super User chat - the most preferable room is Root Access - and ask some user with more than 2k reputation to make the trivial edit for you.
Generally, users without full edit privileges are expected to make very thorough and substantial edits.
Or just "YES" != "NO" (3 characters)
In that case, reconsider. Is simply changing a "yes" to "no" really not going to harm the post in any other way? Will the other sentences make sense? Make sure to respect the original author and don't completely change the meaning of a post. If you think something is completely incorrect, then leave a comment and/or down vote the post. Or provide a better answer yourself.