My sister is quitting her job and wants to quiet quit and also fuck the company over. What can she and can’t she get away with?

Long story short, my sister is constantly verbally abused by her ceo and is planning on quitting after Friday. She wants to delete all the stuff on her computer so they are in a bad place when she leaves but needs to know if there is a line where they can prosecute her legally. Anyone know if she can delete all the files related to her job? Or what can she do?