How to reset OS X back to the Setup Assistant

If you want to factory reset your Mac OS X v10.6 Snow Leopard and older:

1. Press Command-S during startup to get into single user mode
2. Check the filesystem:

# /sbin/fsck -fy

3. Mount the root partition as writable:

# /sbin/mount -uw /

4. Remove the hidden .AppleSetupDone file:

# rm /var/db/.AppleSetupDone

5. a) For Mac OS X 10.5 ‘Leopard’ and newer, do:

# launchctl load /System/Library/LaunchDaemons/com.apple.DirectoryServices.plist

Repeat for every user previously defined on the machine (replace {username} with the real user name):

# dscl . -delete /Users/{username}
# dscl . -delete /Groups/admin GroupMembership {username}

5. b) For older versions of Mac OS X, do:

# rm -rf /var/db/netinfo/local.nidb

6. Remove the home directories of users. For every user do (replace {username} with the real user name):

# rm -rf /Users/{username}

7. If applicable, remove already created files in root’s home directory, e.g.

# rm /root/.bash_history

8. Shutdown (or reboot to verify the procedure worked):

# shutdown -h now

or:

# reboot