Is there a way to get rid of a 4-year-old misdemeanor for hit and run?

The formal procedure for getting rid of a misdemeanor is by filing what is known as an application for expungement.  this is a document that is filed with the parole board that asks them to pardon you for the crime by removing it from your record so that anyone that does a record check will not find this on your record.  one of the reasons that the application is denied is becasue the state wants people to live with their mistakes and have to struggle due to having committed a crime - i.e. not get hired for a job or be precluded from obtaining certain licenses or degrees.  I suggest that you hire  a lawyer to help you put the application together.  Most criminal defense attorneys can help you.

Based on the few details given, it would appear that under California law, you indeed qualify for an "expungement".  That is a clearing of your criminal record.

Here is a link to a site that I think you will find to be of help; it will explain exactly how to go about the process:  http://www.courtinfo.ca.gov/selfhelp/other/crimlawclean.htm#intro

While this is something that you can do for yourself, if paperwork is not your thing you may want to consider hiring an attorney to help you with this.  A mistake in the paperwork could cause your petition for expungement to be denied or, at the very least, delayed.