The antonyms for the phrase "am attorney for" would be phrases involving the opposite or absence of legal representation. This could include, "I am not representing," "I am not the legal counsel for," or "I am not authorized to provide legal advice for." Each of these phrases indicates a lack of affiliation with legal representation, and may be used to indicate that one is not qualified to provide legal counsel or representation in a particular situation. It is important to clearly communicate any legal limitations, as providing legal advice or representation without proper qualifications can carry serious consequences.