I found this on a county clerk’s website in Wisconsin:

You may not be able to expunge your record. Wisconsin law allows a judge to “expunge” a case in only two situations, both involving youthful offenders:

Misdemeanors committed by a person under 21. If the judge ordered expunction upon successful completion of the sentence, the record can be expunged. See §973.015, Wis. Stats.
Adjudication of a juvenile delinquent. A juvenile who has been adjudged delinquent can, upon reaching age 17, petition the judge for expunction of the juvenile adjudication. See §938.355, Wis. Stats. However, WI Circuit Courts Access (WCCA) database does not display juvenile adjudications because they are not public records.
An expunged case is sealed by the clerk of court and is available to be viewed only with a court order. If the judge properly orders a case expunged, any reference to it will be removed from WCCA. A judge has no other authority or power to expunge cases, and there are no similar provisions for other types of cases.

http://www.countyofdane.com/clrkcort/court/faqCriminal.aspx#21