You cannot undo a compiled FPS Creator game it is a one way process, and even if you could it would be of no use to anyone a un-compiled FPSC game is a load of useless letters a numbers in plain text documents and it cannot be compiled in that form. What i think you really want is to distribute the FPM map files and the media needed so others can build and edit your game.
This would actually be against copyrights to do so unless every single piece of media in the game is yours.
Hope that answers the questions.
Windows 7 Pro, Intel Core 2 Duo 2.8Ghz, 4GB DDR3, Dual nvidia SLI 9800GT 1GB, 1.5TB Hard disk, OS installed on solid state drive