How do I correct my error? Can I lift them out and re-pot them? Thank you.
Not a problem at all. Start with the seedlings that stand pretty much alone, widely spaced from the others. With those done, focus on groups and try to remove a group as a cluster with soil intact from the pot and lay the bundle down sideways/horizontally. Then carefully tease out individual seedlings one at a time from the bundle using thumb and one finger on a seed leaf pulling upwards. Tease the roots apart carefully to separate them as you lift. The seedlings will recover quite quickly when transplanted to their own pots.