How do you Change the Administrator User Name and Password if you can not see it on the users list and do not know the previous one?
IMac – Unknown Admin Password on New/Used IMac 2011
administratorimacpassword
Related Solutions
In conclusion, TimeMachine recovery of the entire system to the status before changing admin password worked well. I recovered the old admin password and it worked for Keychain Access as well.
In details; Just in case the recovery doesn't work and I lose the TimeMachine backups somehow, I copied the TimeMachine backup to another external drive. To do that, however, I needed admin password. So, first I had to reset the admin password.
Note: In my case, the destination for TimeMachine backup was a local partition (probably), so I didn't need network password to access it. If it were in network, for example, you would need password that has been lost at step 8. Then this procedure may not work for you. Before actually try the following steps, it may be good to see if you need password for system recovery, following http://support.apple.com/kb/PH14185 (step 5 in this page is the key), but just cancel when you are asked to choose date and time.
- Open the
Time Machinepane inSystem Preferences. ChooseTime Machine > Open Time Machine Preferences… Slide the Time Machine switch to
Off.Restart the Mac with
Command + Rkeys held down to enterRecovery Mode.- In Recovery Mode, launch
Terminal.app. - In Terminal.app, type
resetpassword. - Choose the admin account and set new password. Verify it.
Warning about Keychain will appear.
Restart. Now you get admin password at the cost of loosing Keychain password. The server won't work properly any longer.
- The OS will ask if you want to update Keychain password. Because you don't know the old password. You can't do that. So just choose Continue in the middle.
The system will ask Keychain passwords, but you have to ignore them.
Connect an external drive that is large enough.
- If necessary, reformat the drive to
Mac OS Extended (Journaled). see http://support.apple.com/kb/ht5096 - Click the icon of the new backup drive and choose
Get Infofrom the File menu or press Command-I (⌘-I) - Make sure
Ignore ownership on this volumeat the bottom of theSharing & Permissions:section is not checked. - Open a new Finder window. In the Finder sidebar, click the icon of the current backup drive.
- Open a new Finder window. In the Finder sidebar, click the icon of the new backup drive.
- Drag the folder
Backups.backupdbon the current backup drive to the root level of the new backup drive. - Enter an administrator name and password (you needed to reset the admin password for this step), then click OK to start the copying process. This may take some time to complete because all the backups will be copied.
After the copy has completed, you can eject the eternal drive.
Restart the machine with
Command and Rkeys held down to enterRecovery Mode.- In Recovery Mode, Select
Restore from a Time Machine Backup,then click Continue. - Select the TimeMachine storage.
Select the date and time of the backup you want to restore, then follow the onscreen instructions.
In my case, I successfully recovered admin password as well as default Keychain password.
Security updates are for your security. Unpatched systems are first to be attacked when a new exploit is discovered.
Of course, if you were running in an admin account, these could all be done silently. As you're not, someone has to authenticate every time.
Switch off all updates… in all accounts…
Sign out of the App Store… in all accounts…
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Best Answer
In short, you don't.
That's the entire point of having a secure computer.
The long answer is you have to wipe the machine & start over. Nothing on there belongs to you, not even the OS itself, & you would have to provide the old owner's credentials for any updates.
See Apple KB - What to do before you sell, give away, or trade in your Mac
If you are no longer in touch with the previous owner, you'll have to start from step 6. Fortunately you can actually just start from there on an old Mac. On a new one, you would need to get the original owner to release it first.