Navigating software ownership with your employer can be tricky and depends on various factors. The Computer Fraud and Abuse Act penalizes unauthorized data destruction, even if you initially input the data. Copyright ownership typically lies with the creator, unless under a “work for hire” agreement. Employers may have implied licenses to use your software based on past actions. Seeking legal advice is wise in unclear situations. Trying to negotiate with your employer by showcasing the software’s value or offering ownership for a fee could lead to a positive outcome. However, most personal software projects may not hold as much value as you think.
https://law.stackexchange.com/questions/101283/deleting-software-i-wrote-upon-leaving-employment-of-a-company