That is because the form is probably a "local form." For Los Angeles Courts, see http://www.lasuperiorcourt.org/Forms/pdf/LACIV015.pdf
It is called an affidavit of prejudice. However, use it with caution because if you lose, which is more likely, you may anger the Commissioner.
If you have already appeared, it may be that you "waived" the fact that you have a Comm. on your case. If you appear at court and they ask you to "waive" the right to a judge (or Stipulate to Commissioner) don't do it and they will find a judge to hear your case.
I have found that Commissioners in California are every bit as qualified as judges; so be careful. You may get what you ask for.
If you have voluntarily appeared before the commissioner, then you have stipulated to have your matter heard by a commissioner and you can not change jurists in mid-case. In the future, if you do not want you case heard by a commissioner or judge pro tem, then do not stipulate from the beginning. For now, you’re stuck with the commissioner.
Best of luck to you.
This response is intended to be a general statement of law, should not be relied upon as legal advice and does not create an attorney/client relationship.