Legal Question in Family Law in California

There isn't a form. There are various ways to challenge a judge. If the time has not run, you can do a peremptory challenge when the judge is first assigned, pursuant to Code of Civil Procedure section 170.6. But if the judge has already heard a contested matter, it may be too late.

A lot of this is too complicated to explain here. I suggest you at least speak to an attorney, before doing anything yourself.