Apologies if there is a guide or standard thread that people refer to already but I just want to be fully certain I am doing this correctly. I have to return a 2014 Macbook Pro with Yosemite preinstalled. I migrated my hard drive from an older Macbook Pro to the new one. The most sensitive pieces of data were already encrypted in a secure folder. I did not open the secure folder nor did I open any of the less sensitive files. After the migration was complete I enabled FileVault 2. I set all users with extremely difficult passwords. I restarted the Macbook Pro into recovery mode and launched disk utility and unlocked the hard drive volume. Currently I am erasing any free space with the strictest security option, still waiting for that to finish. After that is complete what are the final steps to completely and securely erasing all of my data off this machine before I return it? Thank you. Update: The erase free space process completed and then I proceeded to erase the Macintosh HD when I got this prompt: are you sure you want to erase the partition and create an encrypted partition I then added another tough password and clicked erase, now all that is left is to reinstall the Yosemite OSX, did I miss anything? Update 2: After downloading the Yosemite OSX it asked me for the disk password, this was the password it asked me to create when asking to create an encrypted partition, I entered it and it installed Yosemite and now it is asking for that Disk Password again. Did I do something wrong? There is a prompt at the bottom of the screen that says if you forget the password, hold power button down, shut down, press it again and start up in Recovery OS. Tried that but it did not make a difference so I used the same password that I set at the encrypted partition stage and now I am at the Welcome page with the different countries. At this point does that password encrypted partition mean anything for any future users? When I return this I both want to securely erase everything and not incur any problems with the store so that they can sell this as a refurb. One other thing, I clicked erase free space first and that took over one hour but after when I tried to erase the Macintosh HD, it only took a couple of seconds, was the erase free space button basically the equivalent of erasing the entire hard drive?