Complete cleaning

[Qonix]

Hi, I'm selling my iMac tomorrow and I have to delete in the best way possible all the contents (I don't want risk the possibility of restoring my files)
The point is that I never did and I have Maverick GM.
What and how should I do?

Thank you

 

[Weaselboy]

If it is a 2010+ machine you can do a command-option-r (hold all three at once) boot to Internet Recovery. Once there start Disk Utility and select the drive itself at the top left (pick the drive name like Seagate 1TB for example) and erase the entire disk. Then quit Disk Util and click reinstall OS. This will put you back on Lion or Mountain Lion (whatever the machine came with). At the end of the install you will see the system setup screen. Just command-q to quit that and shut down.

This will give you nothing but the original OS on the machine.

 

[Qonix]

If it is a 2010+ machine you can do a command-option-r (hold all three at once) boot to Internet Recovery. Once there start Disk Utility and select the drive itself at the top left (pick the drive name like Seagate 1TB for example) and erase the entire disk. Then quit Disk Util and click reinstall OS. This will put you back on Lion or Mountain Lion (whatever the machine came with). At the end of the install you will see the system setup screen. Just command-q to quit that and shut down.

This will give you nothing but the original OS on the machine.

great I'll try!
So like this there is no risk the guy can recover my files?

 

[Weaselboy]

great I'll try!
So like this there is no risk the guy can recover my files?

It would be very difficult to recovery files after this. If you are really super concerned, you can turn on Filevault encryption on Mavericks and wait for it to finish... then afterward do what I described. That would make it pretty much impossible to recover anything.

 

[Alrescha]

So like this there is no risk the guy can recover my files?

At the bottom of the Erase window see 'Security Options'. You can specify that Disk Utility overwrite everything with zeros when it erases. This is probably more than sufficient to your needs. The NSA might be able to get data from the drive after that, but since they already have it, it doesn't really matter...

A.