Is it mandatory that only an atty can represent our closely held C Corporation (Calif) in a lawsuit, or can I, who am not an atty, but am the CEO?

I have had several phone calls and emails already with the atty for the plaintiff and we have established a good repoire. The last email was asking him to have his plaintiff review his complaints (most of them are incorrect) and cancel the lawsuit and work with us dircectly to a fair resolution on few of the items, which were immediately ade compliant. I included this all in my last email to the atty. It appears that it is one of thoses ADA abuse frivolous lawsuits. The first we heard of any plaintiff complaints was being served the summons. Our insurance company is not covering us for these issues. So we''re trying to save all the atty''s expenses. This plaintiff has filed several other similar ones in California. Thank you for your time