It depends on if you are a juvenile or not. Juvenile's rap sheets are generally sealed when they turn 18. Any other rap sheets or other criminal history are assigned an FBI reference number and archived in their files. Persistent offenders just keep adding to the same file number.
If you remain "clean" for at least 7 years (usually 10), most record searches may find it difficult to dig up "dirt" from your past, but it is still there.
Most cases, it is "til death do us part", but depending on the circumstances, you can petition the court to have your records sealed.