How to have a name change with no chance of anyone knowing your old name?

I think this would be possible, but would take some good planning. Many states require the name change to be published in a newspaper either before or after the change takes place. This makes the change quite public. Some states, such as Iowa, do not require this. However, Iowa, as most states would, requires the petitioner to be a resident of the county where they are petitioning the court. So you may have to move for a while to a state that has the laws that suit you. Then there is the matter of court records. You must find a state where this particular type of court record is not publicly accessible. It differs greatly state to state which court records are made available to the public. You can research all of this online, or get a lawyer to assist you. However, keep in mind that no matter what the court practices are, there will still be your high school yearbook out there, your old friends and neighbors, and your aunt who is just dying to tease you by revealing that your name was once Humbert Humperdink. Good luck.