The reason teeth sometimes need to be taken out as part of an orthodontic treatment plan is that there isn't enough room to fit all the teeth into a jaw that has stayed narrow as it grew. We can't always find room for all the permanent teeth in the mouth. Sometimes removing the wisdom teeth is enough to give us the space we need. In other cases, other teeth have to be removed – for example premolars – to make room for rotated front teeth, to correct the bite, or for so-called camouflage. Even if an orthodontist does everything they can to avoid extracting healthy permanent teeth from their patients' mouths, in certain cases this simply isn't possible.
This answer is for general information. Your own case needs an examination by an orthodontist.