Legal Question in Criminal Law in Virginia

Virginia only allows for expungement (removal) of charges that were dismissed or nolle prossed. Any charge for which a person plead or was found guilty remain on their record. Virginia does not remove charges after a certain period of time. Unfortunately there are not a lot of options in that respect. You could appeal the case within ten days from the conviction and try the case again in Circuit Court and try to get it dismissed or make a different plea deal, however if the Commonwealth's Attorney's office (the prosecutor) was involved in the case at General District Court level, it is unlikely that they will make a better offer.

Unless you are allowed by the general district court to withdraw your

plea of guilty and lodge your request for an appeal de novo in the circuit court,

I'd say that you're likely pretty much stuck with the record of the conviction which you apparently agreed to. (And, yes, a petty larceny conviction on your record is likely to have a considerably more detrimental effect on your future than a trespassing conviction----and one not merely limited to your job prospects).