Hey guys, I'm new here, I recently got a bonsai growing kit from Germany, out of 4 seeds, on my this little fella managed to grow, my question is how exactly to take care of it, should I remove the plastic cover or leave it like that? Pls, someone help me, thank you!

... have you planted a bean?
You do know that out of the seeds in your " bonsai kit" there will grow normal trees ?
If you have to ask this question it means that you don't have any horticultural knowledge, so I suggest you start there.
Concerning your seedling - take the lid off if you don't want it to grow through the hole in a few days