Poison Hemlock is a biennial that spreads by seed. If you do not let it grow, bloom and set seed in the vegetable garden and there is a not a patch of it nearby setting seed that blows into the garden you have nothing to worry about. There is no biohazard disposal or soil removal needed. Just don't eat any of it until you are ready.

You can post pictures in the comments to make sure your weed is really Poison Hemlock. The carrot family has a lot of look-alike members. Did it look like this? I had been admiring this statuesque plant in my daily drive and stopped to see if I wanted some. It was Poison Hemlock, Conium maculatum. I haven't decided if I want to collect some seed or not. It is very statuesque.

Garden so far after I have roundup and dug up some of the area that had the hemlock.

Could be. Check for purple speckling on the bigger leaf stems near the crown. What part of the world are you located in? You can still do a vegetable garden this year if you don't dawdle. The hemlock won't taint your vegetables.

Michigan/IN region. It had some purple spots. I was able to get this one before it flowered.