How do i Re-Install El Capitan on my 2011 iMac? Selling iMac

Benz63amg

macrumors 68030
Original poster
Oct 17, 2010
2,952
448
Hey guys, im selling my mid 2011 27 inch iMac and i want to reformat the drive and set up the computer as new for the potential buyer, What is the safest way to do this? Thank you in advance
 

DeltaMac

macrumors G3
Jul 30, 2003
9,606
2,352
Delaware
Boot to your El Capitan installer.
If you don't have a copy of the installer, then just boot to Internet recovery (restart, holding Command-Option-R)
Erase the 2011 hard drive.
Reinstall El Capitan (or whatever system is presented in Internet Recovery, if that's what you want to do)
When the installer reboots to the new user setup, shut your iMac off. Leave that setup for the new owner.
 

Benz63amg

macrumors 68030
Original poster
Oct 17, 2010
2,952
448
Boot to your El Capitan installer.
If you don't have a copy of the installer, then just boot to Internet recovery (restart, holding Command-Option-R)
Erase the 2011 hard drive.
Reinstall El Capitan (or whatever system is presented in Internet Recovery, if that's what you want to do)
When the installer reboots to the new user setup, shut your iMac off. Leave that setup for the new owner.
I only have An actual disc of Lion OSX, should I just reinstall high Sierra for the potential buyer? How do I install a fresh copy of high Sierra?
 

DeltaMac

macrumors G3
Jul 30, 2003
9,606
2,352
Delaware
If you want to to an erase and install High Sierra, then you need to get a copy of the High Sierra installer.
You can download that installer app from this link.
Make a bootable installer using the instructions from this page. I like 8GB flash drives, but 16GB is easier to find now.
Boot to your new installer drive. Erase the internal HD, then reinstall macOS.
[doublepost=1554518548][/doublepost]
I'd just install high sierra. You can download it here:

Get macOS High Sierra

You only need a USB flash drive with 8GB of storage to make an installer USB. Here's how to make one:

https://support.apple.com/en-us/HT201372
Great minds think alike :D
 

Benz63amg

macrumors 68030
Original poster
Oct 17, 2010
2,952
448
If you want to to an erase and install High Sierra, then you need to get a copy of the High Sierra installer.
You can download that installer app from this link.
Make a bootable installer using the instructions from this page. I like 8GB flash drives, but 16GB is easier to find now.
Boot to your new installer drive. Erase the internal HD, then reinstall macOS.
[doublepost=1554518548][/doublepost]

Great minds think alike :D
Is there no simpler way to do it? i havent created a bootable installer in many years, can i just opt to install high sierrra ontop of the current version of El Capitan that i have installed and choose Erase and install and be done with it?

Can i clear my data from the computer without reinstalling the OS? what if i just manually uninstall the programs i have installed?
 

DeltaMac

macrumors G3
Jul 30, 2003
9,606
2,352
Delaware
You DID start by asking about the "safest way to do this". "Safest", to me, is the same as "secure', which then means at least a full erase of the drive. That will assure that your own data and files are for all practical purposes, gone forever.
(Consider that your passwords likely still exist on the drive, difficult to retrieve, for sure, but still there. Full erase is your best bet. Removing random apps, leaving your previous system intact doesn't quite do the trick. Full erase, then reinstall, using the bootable installer is your simple way to the safest result.

The bootable installer is NOT difficult to make, and gives a bit of extra value for the new buyer, if you put that bootable installer in the box when you sell the old iMac. (And, you know that the drive gets erased, because you did that)
 

Benz63amg

macrumors 68030
Original poster
Oct 17, 2010
2,952
448
You DID start by asking about the "safest way to do this". "Safest", to me, is the same as "secure', which then means at least a full erase of the drive. That will assure that your own data and files are for all practical purposes, gone forever.
(Consider that your passwords likely still exist on the drive, difficult to retrieve, for sure, but still there. Full erase is your best bet. Removing random apps, leaving your previous system intact doesn't quite do the trick. Full erase, then reinstall, using the bootable installer is your simple way to the safest result.

The bootable installer is NOT difficult to make, and gives a bit of extra value for the new buyer, if you put that bootable installer in the box when you sell the old iMac. (And, you know that the drive gets erased, because you did that)
The thing is that i havent updated my iMac in a long time which is why its on El Capitan, I much rather re-install El Capitan than upgrade it to High Sierra, How do i do a full restore to El Captian?

i'm afraid something might go wrong during the restore which will corrupt the hard drive or anything like that which will make me then be unable to sell the computer, its been running fantastic on El Capitan all these years
 

eric89074

macrumors regular
Sep 19, 2012
143
147
The thing is that i havent updated my iMac in a long time which is why its on El Capitan, I much rather re-install El Capitan than upgrade it to High Sierra, How do i do a full restore to El Captian?

i'm afraid something might go wrong during the restore which will corrupt the hard drive or anything like that which will make me then be unable to sell the computer, its been running fantastic on El Capitan all these years
If you want to reinstall el cap it’s the same process as high Sierra. It’s very easy to make the usb and install
 

Fishrrman

macrumors P6
Feb 20, 2009
17,481
5,676
Want to do things quick n easy?
Then, do this:

Power down, all the way off.

Press the power on button and hold down command-option-R and KEEP HOLDING IT DOWN until the internet symbol appears.

If you're using wifi, you may need to enter your wifi password.
BE PATIENT -- let the Mac boot to internet recovery.

When you get to the utilities menu, open Disk Utility.

Choose the "topmost item" in DU's list (on the left) that represents the physical hard drive inside the Mac.

Click "erase" and choose Mac OS extended with journaling enabled, GUID partition format. If you want, you can do a "secure erase" to zero out the drive. I wouldn't bother, but this is up to you. It WILL take longer to erase the drive this way. I wouldn't recommend more than "1 pass".

OK, once the drive is erased, close DU and open the OS installer.

Accept whatever OS Apple wishes to install.
If the new owner doesn't want it, he/she can put another one on later.

Let the OS install. It's probably going to take a while and involve one or more reboots.

When done, you should see the initial setup screen, asking what language you wish to use.

At this point, I WOULD JUST PULL THE PLUG OUT OF THE WALL and let it "go dark". By doing this, THE NEXT TIME it boots up (when the new owner does it), it will be like "starting from new".

That's how I'd do it.
Others may disagree.
 

iTarbuck

macrumors member
Jan 29, 2019
32
11
Liverpool, UK.
I only have An actual disc of Lion OSX, should I just reinstall high Sierra for the potential buyer? How do I install a fresh copy of high Sierra?
Go to the app store and update to the latest version of Mojave. Im sure that your buyer will want to install the latest OS version to use the computer, so just do it for them.
 

Benz63amg

macrumors 68030
Original poster
Oct 17, 2010
2,952
448
Thank you for the suggestions and instructions guys, I went ahead and reinstalled El Capitan successfully.