My answer here was not meant to be a Community Wiki answer. Possibly I checked that box by mistake. I wouldn't like the thoughts and examples, especially regarding hail from, ascribed to anyone but me. I take responsibility for my own response,and I would like to do so regarding this answer.
The only way to revoke Community-Wiki status is if a moderator does it. Flag for moderator attention.
I wonder what kind of conditional my first sentence is.
You cannot do this by yourself. Once you've marked an answer as Community wiki, it can be only reversed by a moderator. So that the user knows this, whenever you mark an answer as community wiki, you get a message:
The image above is for Google Chrome. If you're using a different browser, you might get the message in a different way, but the content will be the same.
Now to the point. If you want to reverse this, custom flag the post for moderator attention. If the moderator agrees to make it a normal post (which happens most of the time), your flag will be marked helpful and the post be reversed. If not, the flag will be declined, and the post will still be a community wiki.