Advice needed - caterpillars on my parsley. what do I do?

Hey everyone, I just woke up and went to water my plants, and I noticed 3 caterpillars on my parsley. I dont want to unnecessarily kill them, but also I don't want them to wreak havoc on my little garden, so what should I do?

Update: when i tried to move them i only found one. I moved it outside, but i read that this species feeds in groups. Not sure what the implications of that are. Hope itll be ok