In Cheating To Install Custom Cultures, I mentioned how to add the custom cultures without using CultureAndRegionInfoBuilder.Register().  Should you have any problems with a custom culture / locale and want to uninstall it but are having difficulty with an uninstaller or whatnot, this is how to get rid of it:

{Warning this edits system stuff and could mess up your computer if you aren't careful, or if the custom culture was required by some application.}

Warning, if your locale was installed with the Microsoft Locale Builder installer or another installer, you'll still have to run that uninstaller to make the system happy if you want to reinstall it that way.  In other words, don't use this if it came through an installer.

1) Run intl.cpl (Regional and Language Options) and change to some other locale.

2) Get rid of the custom culture file.

a) Open an elevated command window (eg: press windows key, then type "cmd", then CTRL+SHIFT+ENTER, or right click on cmd and choose "Run as Administrator"

b) "dir %windir%\globalization\*.nlp" to see installed custom locales

c) "rename %windir%\globalization\fj-FJ.nlp fj-FJ.disabled" to disable a custom culture named "fj-FJ" (Fijiian (Fiji)).

d) After rebooting, if desirable you can then "del %windir%\globalization\fj-FJ.disabled".  Often you can't just delete the .nlp file at first because it may be in use.

3) You can also clean the registry key though this isn't necessary, it won't work if it can't find the file:

a) Run regedit (warning: improper use can mess up your computer, etc.)

b) Expand all the + arrow thingies to get to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Nls\CustomLocale (each \ is a new level)

c) Select the value (eg: fj-FJ) you want to delete, then press the delete key.

Hope someone finds this helpful.

Shawn