Normally you would talk to the prosecutor prior to court and see if they would amend to a lesser charge as part of a negotiated plea agreement. If so, when your case is called up the prosecutor will normally take the lead, advise the court of the deal and the court will normally accept it after inquiry is made of the prosecutor and you.

Traffic court prosecutors deal with pro se litigants frequently so just tell them what you are proposing and see if they will accept it.