How do I go about writing a letter or talking to someone about getting my probation switched to unsupervised probation?

Im suppose to be on probation for 2years,I attend college and play sports and I don't have a major criminal record,just to minor misdemeanors,also take care of my two kids everyday. The probation random drug test are time consumig (no fails) ,not a drinker and they have me attending to a week as well as outpatient rehab. So how do I go about getting unsupervised probation?