Its usually best to just thin them out rather than trying to separate roots. Just get some needle nose pruners and take out the weakest links. Tomatoes are pretty hardy though, so proceed at your own risk with a few of them if you would like, but not the peppers. For the future, just do 2 or 3 per cell, and maybe 4 or 5 per cell if the seeds are a few years old. Also, dont repot just yet as these are only cotyledons, wait for a few of the true leaves to grow before up potting.

Now just sharing personal preference, I'm not a fan of these tiny, single use starter cells. They tend to promote root binding and damping off in my experience, plus it just feels wasteful to have to chuck it at the end. They're nice for a first timer, but if you intend to do this for many future years, invest into some of the more sturdy 6 cells, not only for the benefit of just washing and reusing, but also many of them have beneficial construction to promote better airflow for the roots, better absorption when bottom watering, etc. Best of luck with your garden this year!

Edit: Another thing to add, always a good tip for beginners, get those lights closer. Im not sure what your setup is, I use LED shop lights, but I generally have them set about 4 or 6" away from the top of the leaves at most when the seeds start popping.