Different statutes and different courts determine whether to vacate a conviction depending on whether that conviction is a felony (see RCW 9.92.066, 9.95.240, and 9.94A.640) or a misdemeanor (RCW 9.96) or a juvenile offense.The defendant's sentencing court is normally the court that shall hear a motion to vacate a conviction.
In addition to vacating a conviction, you may seek to seal the record of your conviction and should examine the date of your offense since the laws on this issue changed in 1985.
Can any felony conviction be expunged from a criminal record? Can any misdemeanor conviction be expunged from a record?
The short answer to both questions is "no." Violent offenses and felonies identified as a "crime against a person" are normally not subject to expungement. As far as misdemeanors, expungements are normally not allowed for DUIs or related offenses and sex offenses or if you have had another conviction vacated. Whether it be a felony conviction or misdemeanor conviction, a defendant must have completed their sentence and have no pending criminal charges (and wait the specific statutory waiting period) before being eligible to have their conviction vacated from their record.
As far as juvenile offenses, you may to seek to seal the record after the statutory set waiting period unless your offense was a sex offense or a Class A felony or you did not pay the court ordered restitution, and there are no proceedings pending against you and you have complied with all other requirements of law.
Additional resources provided by the author
Besides the RCWs, useful information on this subject is available at GR 15 of the Washington Court Rules and Washington Administrative Code (WAC) 446-16-025 & WAC 446-16-030