It depends. If you are charged with a class B misdemeanor DWI, you may not be able to waive arraignment as there was a recent change in policy instituted by the administrative office of the district courts (that not all courts are adhering to). Also, because you are representing yourself, you may not be able to do it in the same informal manner attorneys do in most cases (by letter). You may have to file a formal motion. And, most likely, you would need the assent (approval) of the prosecutor. Bottom line, you should call the Clerk and get some clarification on this issue, or better yet, speak to an attorney about your specific situation.
Retain a local NH criminal attorney - you will then be protected at all stages of your case.
This is not intended to be legal advise or as legal representation. I am a California personal injury attorney . Be aware that every state has its own statute of limitations; and statutes & case laws that govern the handling of these matters.
Arraignments in New Hampshire are governed by NEW HAMPSHIRE RULES OF CRIMINAL PROCEDURE
Rule 4. Initial Proceedings in District Court. Typically, an arraignment is your first court appearance where you are formally advised of the charge(s) against you and asked to enter a plea of guilty or not guilty.
In district court, an Attorney can waive the arraignment and enter a Not Guilty plea on your behalf. Thereafter, a trial date will be set. Some district courts have "local rules" requiring your presence at these preliminary hearings to address issues of bail and other matters.
If you are charged with a felony offense a not guilty plea will be entered as the district court does not have the authority to resolve a felony offenses. A probable cause hearing will then be scheduled in the matter.
At each step of this process, being represented by a criminal defense lawyer who knows the local rules is a wise choice.
DISCLAIMER- THIS IS NOT INTENDED TO AND DOES NOT CONSTITUTE LEGAL ADVICE AND DOES NOT ESTABLISH AN ATTORNEY-CLIENT RELATIONSHIP. CONSULT A QUALIFIED LEGAL COUNSEL IN YOUR CITY OR STATE FOR IMMEDIATE LEGAL ADVICE.