I just pluck them out with a small spoon or a chopstick while they are still pretty small. It works well, I did this for some years already.

But if you wait too long the roots get bigger and tangled, so it’s a bit more effort because I usually transplant early into a small pot and then repot them later into a bigger pot. I try to save space while growing from seed because our last potential frost date is mid may and there’s not so much space on our south windowsills where I put all my seedlings. So it does get crowded with fennel, zucchini, peppers/chilis and the tomatoes.