Isn't that nice? I thought I was going to get advice from a licensed attorney. Does just anyone who visits here practice law?
Yep, there are a few. But, they are not going to give "legal advice" as they are not YOUR attorney.
Have you even check with the DFEH and asked what YOUR options are in response to the complaint?
And understand that you CAN sue the complaining party ... ANYONE can sue almost anyone else for most anything. The problem is prevailing. You will not only have to find legal grounds on which to sue this person, but you will also have to articulate damages. You cannot say that you MIGHT one day be damaged by the allegation and expect an award.
if you feel you have a case consult an attorney. I suspect you are going to be told that the complaining party has a right to make a complaint.
If you feel that the allegations were knowingly and intentionally slanderous, perhaps you have grounds to sue. But, the burden of proof will be on you. Plus, you will have to hope that the other party has the money to pay any award that might be obtained. In a case without damages, it is more likely that your attorney's fees would be awarded but you might strike out unless punitive damages are awarded.
Understand that people can make complaints. They can also hold opinions they do not like. I'm in law enforcement. If someone makes a complaint claiming I am a racist and a fascist, I have to live with it. I can no more prove I am neither than they can prove that I am either. But, their opinion can still be valid. What will be at issue will not be whether you are racist, but whether your actions were lawful and based upon established law and guidelines and NOT based upon racial bias (or some other unlawful conduct).
But, feel free to consult a local attorney. Perhaps the person wrote complete fabrications. But, if they wrote an interpretation of events and then attributed it to a perception that you were some sort of racist, you are likely left with no recourse outside the DFEH process.