[asheshouse]

I've done this recently starting from UI 1.2 install and converting back to 4.08

Run the Version Switcher to switch to 4.08 mods off (original)
Start the game to confirm it starts in 4.08 version.

Delete root\MODS folder
Delete root\Maps folder -- if you have one
Delete root\files folder -- if you have one

That's it.

If you now patch this with the latest official 4.09m version (Team Daidalos)
copy the new files.sfs and il2fb.exe into your _game_switcher/4.09 mods off folder

You can now still use the Version Switcher utility to switch between 4.08 and 4.09 unmodded.

Ashe