Alhamdulilah you have realized the error of not wearing hijab. It is possible that there will not be a sin upon you for old pictures inshallah.
You should however try your hardest to get any of these pictures removed. Try to privately message the person who had tagged you and explain the situation. If they refuse to remove these pictures, then they will be in violation of your rights and they will be also committing a sin if they are Muslims.
It may also be possible to message the social media platform and request a removal. All you can do is try and if it isn’t successful, you have fulfilled your duty.
May Allah grant you success