If you’re talking about the one from the barbarian tribe I’m pretty sure he takes it off after leaving near the end of season 1 ((?)I forgot if the season ends with him coming back to his family)
I remember him wearing it when he was in the academy
Based off the latest chapter thus far, and if my memory isn’t an eyeless mole rat, I don’t think I saw him with a collar in the academy at least, mostly because it’d be seen as odd seeing a fellow classmate wear a slave (?) collar
Is he still wearing the collar?