Hello, everyone I'm a new Mac user and a new member of MacRumor forum. I DO REALLY NEED A HELP from you the more experienced users to solve my problem. I'm trying to explain it as compact as I could. So here it is: BACKGROUND: I'm resigning from my current work office. Hence I don't want to leave any traces or private data (such as login items, iPhone backups, pics, songs, etc) remains in the company's iMac. So I think the best way to get rid all of it is to perform complete disk reformat and to reinstall the OS X afterward. WHAT I'VE DONE: - Backup all my private data - Performed secure empty trash after I backup all those private files. - Cleaned cache using CleanMyMac 2 (I know.. I know.. but I don't have many options right now) - Deauthorize my computer from iTunes - Uninstall all third-party apps CHALLENGE: - My administrator is a prick. He's a pervert and too lazy to help me solve the problem. He notoriously known as a person who'd like to dig in on personal data of someone else who works on the company. When I was telling the administrator about my plan to reformat the iMac, he quickly warned me to not perform the action. He told me that the company will GET TROUBLED FOR THE LICENSE. - I've removed securely some of my personal files yesterday. But since I'm new to this method, I worry how about my other personal data that I've deleted long time ago without this method. QUESTION: Is there any way to get rid COMPLETELY of my personal data and make them impossible to be recovered without being tangled with the license issue? Is there any way to reinstall Mac OS X safely enough regarding my background here? In order to get better understanding about my iMac, I attach some of my systems screenshots. Looking forward for your help, guys. Thank you so much.