What do we need to do to vacate the legal separation judgement?

Qualifying facts. You probably don't have them. You are still married. The judgment is misconceived by the learned geniuses of the legal profession who act like plumbers. The judgment is actually merely an adjudication of assets, liabilities, and community property rules. You remain married but without the application of community property rules; if you want those rules to apply as if you were newly married and/or never subject to the Judgment you should get a brief marital agreement so stating drafted by a family law attorney.