I can't log in to my older model iMac All-in-One 27-inch desktop because I don't know the previous owner's password. The previous owner passed away and her mother who gave it to me doesn't know what it is.
Earlier Mac models
Just a guess – but you might need to give the Mac back, and have the previous owner's mother or the executor for the previous owner's estate regain access to the Mac. This might involve contacting Apple and providing whatever legal documentation Apple requires for security and verification purposes.
If you forgot your Mac login password - Apple Support
If you can't reset your Mac login password - Apple Support
How to request access to a deceased family member's Apple account - Apple Support
After they recover access to the Mac, they should prepare it properly for transfer back to you.
What to do before you sell, give away, trade in, or recycle your Mac - Apple Support
Just a guess – but you might need to give the Mac back, and have the previous owner's mother or the executor for the previous owner's estate regain access to the Mac. This might involve contacting Apple and providing whatever legal documentation Apple requires for security and verification purposes.
If you forgot your Mac login password - Apple Support
If you can't reset your Mac login password - Apple Support
How to request access to a deceased family member's Apple account - Apple Support
After they recover access to the Mac, they should prepare it properly for transfer back to you.
What to do before you sell, give away, trade in, or recycle your Mac - Apple Support
If it is an older model iMac without a T2 security chip (2019 & earlier), then there is no need to know or reset the password as long as a firmware password lock has not been enabled. Just boot into Internet Recovery Mode using Command + Option + R to access the online macOS installer for the most recent version compatible with that Mac although some Macs may only boot to the online installer for the older version of macOS which shipped from the factory. The trick is to select the whole physical drive (or Fusion Drive) and erase it using Disk Utility. Within Disk Utility you may need to click "View" and select "Show All Devices" before the physical drive appears on the left pane of Disk Utility. Erase the physical drive (or Fusion Drive item if present) as GUID partition and APFS (top option) for macOS 10.13+. Quit Disk Utility, then select the "Install macOS" or "Reinstall macOS" option.....Do not restart the computer after erasing the internal drive.
Unfortunately a T2 Mac (2020 iMac) will always prompt for an admin password even when booting into Recovery Mode. I don't know what happens if you perform a DFU firmware Restore since that will reset the T2 security chip & system firmware and erase the internal SSD. Afterwards you must boot into Internet Recovery Mode to properly erase the SSD as described earlier & reinstall the OS.
However, it may be worthwhile to attempt to have Apple reset the Mac by showing the previous owner is deceased. If that fails, then try the steps I have presented since there is nothing left to lose at that point.
The computer needs to be setup per the directions in What to do before you sell, give away, trade in, or recycle your Mac - Apple Support
However before you can even do that you need to take it to an Apple Store and have following done: How to request access to a deceased family member's Apple account - Apple Support
Before these 2 things are completed, all you have is a boat anchor as the computer is still tied to the daughters Apple ID account.
Thanks a lot for getting back to me so quickly. I have found a couple of ways to bypass this issue, I just haven't tried anything as of yet. Your suggestion sounds the easiest though. Thanks again.
My neighbor's daughter passed away and she gave me her iMac 27 inch All-in-One desktop computer. My issue is they don't know her password so I can't sign in to set it up so I can use it. Help!!! LOL!!!
