Pursuant to Idaho Code §19-2604, if you successfully completed your probation without issue and you can show good cause, you may have your case retroactively dismissed. This means that instead of "Guilty" the record will read "Dismissed By Court."
While this might not completely erase all record of the case, I have had a very high success rate with this option. It is effective in cleaning up my client's records and it is relief that the court is willing to provide. This is often considered the best option for people seeking to have their record "expunged."