Legal Question in Real Estate Law in California

First, I must caution you that there may be a difference of opinion between the neighbor and you over whose property the fence is on. Are you sure? Maybe a survey is indicated. A fair proportion of these "trespass by fence" cases end up involving one party's mistake as to where the property line really lies. If indeed the fence is partly or completely on your property, it is an instance of trespass; you don't own it, but you have a legal right to have it removed, including the right to remove it yourself if absolutely necessary and this can be done without provoking a disturbance of the peace.