3/15!!! Ok, I'm a month behind. I was reading your post and thinking - 2 week old chicks outside!! NO WAY! 🤣
Yes - 6 weeks is probably doing them more harm than good with the light.
You are safe to unplug the light and monitor their behavior. I'd say they are still a little young to be put outside with nighttime temps, assuming those temps are 40 to 50 right now, with no supplemental heat.
If you see them piling up with unsettled movement within the group they are too cold.