If you sowed straight into a small pot, then you need to remove all but one to allow it to grow to maturity. If you sow into a seed tray, spreading a pinch or two of seeds evenly, when they germinate and get two sets of leaves, you prick those out into individual pots to grow on. You can try pricking out some of the others in your pot if they have 2 sets of leaves, but one seedling to a pot is necessary.
Next time you sow seeds, bear in mind that each seed represents one plant - depending which chamomile you're growing, each seed means a plant that grows to 4 inches or 20 inches high, by 18 to 24 inches - in order to do that, each one needs to develop its own extensive root system. Sowing into a pot, you only needed to plant four to six seeds maximum, removing all but the strongest one as they grew.