Hello.. I've completed the game, and i usually uninstall the game when i finish one.. But it is as if GOG hasn't put in an uninstall funktion.. I see it but when i click it nothing happens..

Did you try the control panel > Add / Remove program?
Open task manager to see is any uninstall, setup, or something similar is running.
Wait for a few minutes and let the computer run for a while.
If none of them happen, try to re-install and uninstall again.