Is a Muslim woman obligated to contact her non-Muslim friends to request the deletion of immodest photos of her published before she embraced Islam, or is that among the things that are forgiven for her?

Islam obliterates the sins that preceded it, and so does repentance. Therefore, whoever perfects his Islam will not be held accountable for what he did in the جاهلية (pre-Islamic era). The meaning of perfecting one's Islam is to embrace Islam outwardly and inwardly. A Muslim should rectify whatever can be rectified from his past actions. Regarding the issue of pictures, if a picture is stored with those whom she associated with before Islam, she may request its removal if she believes it will be removed; otherwise, silence is preferable.