How do I uninstall or downgrade from OS X Lion Server?

Since the server component changes files and preferences, you can't easily undo those changes other than by a back up. There is no uninstall - and there are in general no way to undo any patch or upgrade - even between major revisions like 10.6.7 to 10.6.8.

The only sure way is to restore those settings and files that get changed from a backup or set things up after a totally clean installation.

Boot into recovery, erase the volume and install Lion (without the server component) and you will have a correct and complete non server Lion. You can migrate data in from external drives, time machine (at any point in time) or make the set up new by hand.

Lion will not allow a simple re-install to "undo" the server changes as it's not programmed to do all that work in reverse.

lsbom  -p F /var/db/receipts/com.apple.pkg.Server*.bom | perl -pi -e 's/\.//'

Gives you the files installed by the Server packages, in double quotes, absolute paths.

(Edited version)

To uninstall OS X Lion Server, it depends on the server state. If the server is not configured, one need only to delete the Server app from the Applications folder, and restart the machine.

(I have tried this. It works except for one thing. In the AppStore, you will always get a notification when the server app can be updated.)

If the server has been configured, I can only point you to this apple support document:

http://support.apple.com/kb/HT4827

Please note that this article refers only to disabling Server, not removing it.

Once you have configured the Server app it will download and install its components which are not deleted with the app.

Server app is just an interface to these individual control modules similar to command line tools or like preferences items that plug into the server.app

You can use the above method to look for the files that the server.app downloaded but I doubt if you can straightaway delete them.

The Server.app once configured will mark your OS X Lion as OS X Lion Server and you will continue to receive server related update alerts even if you delete it.

/System/Library/CoreServices/ServerVersion.plist

This file is created when you configure the server and OS X Lion will look for it while checking for the software updates.

If you delete this file OS will fallback to "SystemVersion.plist" in the same folder and your machine should be back to non server updates :)